Torque transmitting apparatus

ABSTRACT

A torque transmitting apparatus which can be used in the power train between the prime mover and the transmission of a motor vehicle has a first flywheel connectable to the prime mover, a second flywheel coaxial with and receiving torque from the first flywheel by way of a damper, and a friction clutch which can be engaged to transmit torque between the second flywheel and the input element of the transmission. The energy storing elements of the damper and the bearing between the two flywheels are installed radially inwardly of the friction surfaces of the second flywheel and the axially movable pressure plate of the friction clutch. This renders it possible to reduce at least the radial dimensions of the apparatus without reducing the diameters of the friction surfaces.

CROSS-REFERENCE TO RELATED CASE

This is a continuation of the patent application Ser. No. 08/262,620filed Jun. 20, 1994 for “TORQUE TRANSMITTING APPARATUS” and now U.S.Pat. No. 5,622,245.

BACKGROUND OF THE INVENTION

The present invention relates to torque transmitting apparatus ingeneral, and more particularly to improvements in torque transmittingapparatus wherein a first flywheel can receive torque from a rotaryoutput member of a prime mover (e.g., from the crankshaft or camshaft ofan internal combustion engine in a motor vehicle), wherein a secondflywheel is rotatable with and relative to the first flywheel about acommon axis, and wherein rotation of the flywheels relative to eachother is opposed by one or more dampers. The second flywheel cantransmit torque to a rotary input element (e.g., to the input shaft of avariable-speed transmission in the power train between the engine andthe wheels of a motor vehicle), and the transmission of torque from thesecond flywheel to the input element can take place by way of anengageable and disengageable friction clutch.

The invention also relates to improvements in friction clutches whichcan be utilized in the above-outlined torque transmitting apparatus orin other types of torque transmitting apparatus to transmit torque or tointerrupt the transmission of torque between a prime mover and one ormore driven units, e.g., between an engine and the wheels of a motorvehicle.

Still further, the invention relates to improvements in means (e.g., oneor more dampers and/or one or more friction generating devices, such asslip clutches) which can be utilized in the above-outlined or othertypes of torque transmitting apparatus to predictably oppose therotation of several masses (e.g., two or more flywheels) relative toeach other.

OBJECTS OF THE INVENTION

An object of the invention is to provide a torque transmitting apparatuswhich is simpler and less expensive than, but at least as reliable as,heretofore known torque transmitting apparatus.

Another object of the invention is to provide a torque transmittingapparatus which is constructed and assembled in such a way that itsspace requirements in the direction of the axis of rotation of itsparts, as well as in directions radially of such axis, are less than inconventional torque transmitting apparatus.

A further object of the invention is to provide a torque transmittingapparatus which can embody a friction clutch with large-diameterfriction surfaces in spite of the compactness of its constituents indirections radially of the axis of rotation of the rotary parts.

An additional object of the invention is to provide a torquetransmitting apparatus which employs one or more friction clutches withfriction surfaces having radii at least matching the radii of frictionsurfaces in heretofore known bulkier and more expensive frictionclutches.

Still another object of the invention is to provide a torquetransmitting apparatus whose useful life is longer than that ofheretofore known torque transmitting apparatus.

A further object of the invention is to provide a power train which canbe utilized in motor vehicles as a superior substitute for heretoforeknown and used power trains.

Another object of the invention is to provide a novel and improvedmethod of assembling and installing the above-outlined improved powertrain and/or its constituents.

An additional object of the invention is to provide a conveyance, suchas a motor vehicle, which embodies a power train utilizing theabove-outlined torque transmitting apparatus.

Still another object of the invention to provide a novel and improvedmodule which embodies the above-outlined power train and can beconveniently affixed to or detached from a rotary output element of aprime mover, e.g., a crankshaft or a camshaft driven by the combustionengine or another motor in an automobile or another vehicle.

A further object of the invention is to provide a novel and improvedmethod of making the component parts of the above-outlined torquetransmitting apparatus.

Another object of the invention is to provide a novel and improvedfriction clutch which can be utilized in the above-outlined torquetransmitting apparatus and/or in other apparatus to transmit torque orto interrupt the transmission of torque between a prime mover and one ormore driven assemblies.

An additional object of the invention is to provide a torquetransmitting apparatus whose reliability at least matches that ofconventional apparatus, even though it can comprise or actuallycomprises a much smaller number of parts or groups of parts.

Still another object of the invention is to provide a torquetransmitting apparatus whose component parts can be mass-produced inavailable machines and with minimal losses in material.

A further object of the invention is to provide a torque transmittingapparatus which can be practically fully assembled at the manufacturingplant and can be assembled of parts which require a minimum oftreatment, or no treatment at all, in material removing machines so thatthe making of the apparatus can be carried out without adverselyaffecting the surrounding atmosphere.

Another object of the invention is to provide an apparatus which isdesigned in such a way that the making of its parts and/or the assemblyof such parts into an operative torque transmitting apparatus can beautomated to any desired extent.

An additional object of the invention is to provide a torquetransmitting apparatus which is constructed and assembled to reliablyprevent excessive stressing of its constituents, for example, to preventthe transmission of excessive torque from one or more driving parts tothe corresponding or associated driven part or parts.

Still another object of the invention is to provide an apparatus whichis constructed and assembled in such a way that its constituent orconstituents (e.g., a flywheel or a friction clutch) cannot transmitexcessive torque to a variable speed transmission and/or other part orparts in the power train of a motor vehicle.

A further object of the invention is to provide a novel and improvedconnection between the housing and the pressure plate of a frictionclutch which can be utilized in the above-outlined torque transmittingapparatus or elsewhere.

Another object of the invention is to provide a novel and improvedsystem for effectively cooling a torque transmitting apparatus of theabove-outlined character.

An additional object of the invention is to provide novel and improvedenergy storing means for use in dampers between the flywheels which areused in the above-outlined or other torque transmitting apparatus.

Still another object of the invention is to provide a novel and improveddistribution of component parts in the above-outlined torquetransmitting apparatus and to afford convenient access to certaincomponent parts of such apparatus, either to facilitate rapid assemblyand mounting on a rotary output element or to facilitate rapiddetachment of the apparatus from the output element.

A further object of the invention is to provide a novel and improvedcombination of pressure plate, clutch spring and housing in a frictionclutch which can be put to use in the above-outlined apparatus.

Another object of the invention is to provide the above-outlined torquetransmitting apparatus with a friction clutch which automaticallyadjusts the positions of its parts to compensate for wear so that thefriction clutch can remain encapsulated during the entire useful life ofthe machine, e.g., a motor vehicle, wherein the torque transmittingapparatus is put to use.

SUMMARY OF THE INVENTION

One feature of the present invention resides in the provision of anapparatus which is designed to transmit torque and comprises a firstflywheel connectable with a rotary output element (e.g., a camshaft or acrankshaft) of a prime mover (e.g., a combustion engine under the hoodof a motor vehicle), and a second flywheel which is rotatable with, aswell as relative to, the first flywheel about a common axis and isconnectable with a rotary input element of a driven unit (e.g., with theinput shaft of a variable-speed transmission in the power train betweenthe engine and the wheels of a motor vehicle). The transmission oftorque from the second flywheel to the input element preferably takesplace by way of a friction clutch having one or more annular frictionsurfaces disposed at a first radial distance from the common axis of theflywheels. The improved apparatus further comprises a bearing which isinterposed between the first and second flywheels and means for opposingrotation of the first and second flywheels relative to each other. Suchopposing means comprises at least one damper having at least two energystoring elements disposed at least in part in an at least substantiallysealed chamber and extending in a circumferential direction of theflywheels at a second radial distance from the common axis which is lessthan the first radial distance.

The arrangement can be such that the energy storing elements have firstportions disposed at a greater radial distance and second portionsdisposed at a lesser radial distance from the common axis of theflywheels, and that at least the first portions of the energy storingelements are confined in the chamber. The chamber is preferably boundedby a surface including a portion conforming to and adjacent the firstportions of the energy storing elements.

The chamber is preferably defined by an enclosure having at least twowalls at least one of which is connected (e.g., welded or otherwisebonded and/or riveted) to the second flywheel. The arrangement can besuch that the at least one wall supports the second flywheel.

The aforementioned bearing can include or constitute a friction(sliding) bearing and/or an antifriction (e.g., roller, ball or needle)bearing.

At least one of the energy storing elements can include or constitute atleast one coil spring or at least one torsion spring.

The aforementioned enclosure which defines the chamber for the energystoring elements of the at least one damper can be designed in such away that it comprises a radially outer portion disposed at a greaterdistance and a radially inner portion disposed at a lesser distance fromthe common axis of the flywheels. At least the inner portion of theenclosure is or can be at least substantially sealed so that a supply ofdry lubricant (e.g., graphite powder) or a supply of viscous lubricant(e.g., grease, paste or highly viscous oil) which at least partiallyfills the chamber is prevented from leaving the chamber. The means forsealing the chamber from the atmosphere can include at least onelabyrinth seal, at least one membrane, at least one diaphragm springand/or a bonded seam.

The enclosure can be designed in such a way that at least a portion ofthe bearing is also confined in its chamber. Such bearing is or can beinstalled between the two flywheels at a third radial distance from thecommon axis of the flywheels, namely in such a way that it is locatedradially inwardly of the energy storing elements forming part of the atleast one damper.

The enclosure can comprise first and second walls which are connected(e.g., welded or otherwise bonded) to each other radially outwardly ofthe energy storing elements. Such enclosure can further comprise atleast one sealing element (e.g., an O-ring) which is installed betweenthe two walls radially inwardly of the energy storing elements.Furthermore, one or more analogous seals can be installed between thetwo walls of the enclosure radially outwardly of the energy storingelements.

The wall or walls of the enclosure can be provided with one or moreabutments for the energy storing elements in the chamber so that, if theenclosure is affixed to the second flywheel, the energy storing elements(which can receive torque from an input member of the at least onedamper rotating with the first flywheel) can transmit torque to thesecond flywheel (which, in turn, transmits torque to the input elementby way of the friction clutch) in response to rotation of the firstflywheel (i.e., in response to rotation of the output element of theprime mover). The abutments can constitute or include pairs ofconfronting depressions which are provided in the wall or walls of theenclosure and extend substantially in the direction of the common axisof the flywheels, into the chamber, and between the energy storingelements in the chamber.

The at least one wall of the enclosure for the energy storing elementscan be connected (either directly or indirectly) with the secondflywheel. Such wall or walls can be disposed at that side of the secondflywheel which faces away from the at least one friction surface of theclutch. The second flywheel preferably constitutes or carries acounterpressure plate of the friction clutch, the at least one frictionsurface of such clutch can be provided on the second flywheel, andanother friction surface of the friction clutch is then provided on anaxially movable rotary pressure plate of the friction clutch.

The connection between the wall or walls of the enclosure and the secondflywheel can be a form-locking connection. Alternatively, one or morewalls of the enclosure can be in mere frictional engagement with thesecond flywheel.

The input member of the at least one damper can constitute a portion ofthe first flywheel, and such a portion transmits torque to the energystoring elements in response to rotation of the first flywheel, i.e., inresponse to rotation of the output element of the prime mover. Suchapparatus can further comprise means for limiting the magnitude oftorque which is being transmitted by the second flywheel to the frictionclutch. The torque limiting means can be installed between a wall of theenclosure which receives torque from the energy storing elements and thesecond flywheel. One presently preferred embodiment of the limitingmeans comprises at least one friction generating member (e.g., a brakeshoe or the like) which is installed between the enclosure and thesecond flywheel, preferably at least partially outwardly of the energystoring elements and at least partially radially inwardly of the atleast one friction surface of the friction clutch. The limiting meanscan further comprise means for biasing the second flywheel and/or theenclosure against the at least one friction generating member, and suchbiasing means can comprise one or more diaphragm springs. The biasingmeans can be designed in such a way that it is actuatable to urge thesecond flywheel and/or a wall of the enclosure against the at least onefriction generating member. The means for actuating the biasing meanscan be operated by the first flywheel, and at least a portion of suchactuating means can form part of the primary flywheel, e.g., it can beof one piece with the first flywheel.

If the enclosure defining the chamber for the energy storing elements ofthe at least one damper is designed to receive torque from the energystoring elements, the apparatus can further comprise friction generatingtorque transmitting means interposed between the enclosure and thesecond flywheel to transmit torque from the energy storing elements tothe friction clutch by way of the second flywheel. The frictiongenerating means can contain a suitable heat insulating material.

The only wall or at least one wall of the enclosure can be mounted onthe bearing between the two flywheels.

The at least one damper can further comprise an input member (e.g., oneor more substantially flange-like parts) which extends into the chamberto transmit to the energy storing elements torque in response torotation of the first flywheel, and such input member can be connectedto the first flywheel radially inwardly of the energy storing elements.The means for fastening the torque transmitting apparatus to the outputelement of a prime mover can include a set of fasteners (e.g., threadedfasteners in the form of screws or bolts and hereinafter called boltsfor short) and such fasteners can serve to affix the first flywheel tothe output element as well as to affix the input member of the at leastone damper to the first flywheel.

The input member of the at least one damper can comprise a plurality offlanges or like parts having radially outer portions connected to eachother, and at least one of the flanges can comprise at least oneprojection (e.g., in the form of an arm) which extends into the chamberto transmit torque to the energy storing elements in response torotation of the first flywheel. At least one of the flanges is connectedwith the first flywheel, preferably radially inwardly of the energystoring elements. The flanges can include portions which are disposed inthe region of the fastening means and are closely adjacent each other.Each of the flanges can comprise a portion which extends into thechamber to transmit torque to the energy storing elements in response torotation of the first flywheel, and such flanges can further compriseportions which are spaced apart from each other in the direction of thecommon axis of the flywheels and are disposed at least in partintermediate the fastening means and the energy storing elements.

The energy storing elements can comprise coil springs each having twoend convolutions and one or more intermediate convolutions between theend convolutions. The aforementioned portions of the flange or flangesforming part of or constituting the input member of the at least onedamper and serving to transmit torque to the coil springs are preferablyconfigurated in such a way that they transmit torque to the neighboringend convolutions in response to rotation of the first flywheel withoutappreciably changing the orientation of the engaged end convolutionsrelative to the respective additional convolutions.

The at least one damper can be constructed in such a way that its energystoring elements comprise first coil springs and second coil springs atleast partially within the respective first coil springs. The inputmember of such damper receives torque from the first flywheel, eitherdirectly or indirectly, and includes first and second portions whichextend into the chamber to respectively transmit torque to the first andsecond coil springs in response to rotation of the first flywheel. Atleast one wall of a multiple-wall enclosure or the only wall of asingle-wall enclosure which is connected to the second flywheel cancomprise first and second abutments which extend into the chamber torespectively receive torque from the first and second springs of theenergy storing elements in response to rotation of the first flywheel.The first abutments can include deformed portions of the wall whichextends into the chamber, and the second abutments can constitute orinclude deformed parts of the deformed portions.

The input member (e.g., an input member including one or more flanges)of the at least one damper can include or can be mounted on suitablemeans for centering the input member on the first flywheel.Alternatively, the improved apparatus can comprise means for centeringthe input member of the at least one damper directly on the outputelement of the prime mover which drives the first flywheel. Stillfurther the input member of the at least one damper can be designed tosupport the bearing which is installed between the two flywheels.

The at least one damper can comprise a plurality of input members whichtransmit torque to the energy storing elements of the damper in responseto rotation of the first flywheel. At least one of these input memberscan include means for connecting the first flywheel to the input elementof the prime mover, means for centering the first flywheel on the outputelement of the prime mover, means for supporting the bearing, and meansfor centering the second flywheel.

The means for sealing the chamber for the energy storing elements of theat least one damper can comprise at least one sealing element (e.g., adiaphragm spring) which is disposed radially inwardly of the energystoring elements between the wall, or one wall, of the enclosure and thesingle input member or one of several input members of the at least onedamper. If the enclosure comprises two or more walls, one of the wallscan be engaged by the aforementioned sealing element and the other wall(or another wall) of such enclosure can be connected with the one walland with one of the flywheels. One of the plural walls of the enclosurecan include means for maintaining the fastening means in a predeterminedposition relative to the first flywheel.

The only wall or at least one of two or more walls of the enclosure canbe provided with openings, one for each bolt of the fastening means, andeach bolt extends through the respective opening.

The enclosure which defines the chamber for the energy storing elementsof the at least one damper can be designed in such a way that its singlewall or at least one of its plural walls is provided with openings whichare positioned to permit the passage of a tool (e.g., a motor-operatedscrew driver) having means for rotating the bolts of the means forfastening the first flywheel to the output element of the prime mover.The wall or walls which are provided with such openings can includecollars which surround the openings. The enclosure can further compriseat least one sealing element for the chamber, and such at least onesealing element can be disposed in the region of the aforementionedopenings.

The means for sealing the chamber can include at least one diaphragmspring forming part of a friction generating device which is installedto operate between the flywheels.

The energy storing elements of the at least one damper can be disposedin a common plane extending at right angles to the common axis of theflywheels, and the at least one friction surface can be provided on thesecond flywheel at least close to the common plane for the energystoring elements.

The heads of the bolts which form part of the means for fastening orsecuring the first flywheel to the output element of the prime mover canbe disposed in a common plane which is normal to the common axis of theflywheels, and the bearing can be disposed in or at least close to suchplane.

The distribution of various parts of the improved torque transmittingapparatus can be such that the heads of the bolts are disposed in orclose to a plane extending at right angles to the common axis of theflywheels, that the at least one friction surface of the friction clutchis disposed at such plane, and that the energy storing elements of theat least one damper are disposed radially between the heads and thefriction surface(s).

At least a portion of the input member of the at least one damper can bedisposed between the bolts of the fastening means and the chamber forthe energy storing elements.

The input element of the transmission can be provided with axiallyparallel flutes or with another suitable profile for engagement by theclutch disc or clutch plate of the friction clutch, and such profile isdisposed at a first radial distance from the common axis of the twoflywheels when the friction clutch is properly connected with and isready to transmit torque to the input element. The bearing is disposedat a second radial distance from the common axis, and the bolts of thefastening means are disposed at a third radial distance from the commonaxis. The enclosure which defines the chamber for the energy storingelements of the at least one damper includes a radially inner portionwhich is disposed at a fourth radial distance from the common axis, andthe energy storing elements are disposed at a fifth radial distance fromthe common axis. The enclosure further includes a radially outer portionwhich is disposed at a sixth radial distance from the common axis, andthe at least one friction surface (on the second flywheel or on thepressure plate of the friction clutch) is disposed at a seventh radialdistance from the common axis. In accordance with one presentlypreferred embodiment of the invention, at least four of theabove-enumerated seven radial distances are different from each other.For example, the construction of the apparatus can be such that thesecond radial distance exceeds the first radial distance, that the thirdradial distance exceeds the second radial distance, that the fourthradial distance exceeds the third radial distance, and so forth.

Furthermore, the profile of the input element can have a first diameter,the bearing can have a different second diameter, the heads of the boltscan form a circle having a third diameter different from the first andsecond diameters, the radially inner portion of the enclosure can have afourth diameter which is different from the first to third diameters,the energy storing elements can form an annulus having a fifth diameterdifferent from the first to fourth diameters, the radially outer portionof the enclosure can have a sixth diameter different from the first tofifth diameters, and the at least one friction surface can have aseventh diameter different from the first to sixth diameters.

At least four of the above-enumerated parts, namely the profile of theinput element of the transmission, the bearing, the bolts, the radiallyinner portion of the enclosure, the energy storing elements, theradially outer portion of the enclosure and the at least one frictionsurface, are or can be located at least close to a plane which is normalto the common axis of the flywheels when the clutch is properlyconnected with the input element.

It is also possible to construct and assemble the improved torquetransmitting apparatus in such a way that the bolts are disposed at afirst radial distance and the bearing is disposed at a lesser secondradial distance from the common axis of the flywheels. Thus, the bearingcan be installed closer to the common axis than the bolts or vice versa.

Still further, it is possible to design the apparatus in such a way thatthe bolts are disposed at a first radial distance from the common axisof the flywheels, that the bearing is disposed at a lesser second radialdistance from such axis, and that the energy storing elements of the atleast one damper are disposed at a third radial distance from the commonaxis, namely a distance exceeding the first distance.

The common plane of the heads of the bolts can be at least close to orcan coincide with the common plane of the energy storing elements.

It is also possible to construct and assemble the improved torquetransmitting apparatus in such a way that a portion of the enclosure islocated at a first radial distance from the common axis of theflywheels, that the energy storing elements are disposed at a differentsecond radial distance from the common axis, and that the bolts arelocated at a third radial distance from such axis. The first distancecan exceed the third distance and can be less than the second distance.

As already mentioned above, the bearing can be disposed at a greater orlesser radial distance from the common axis of the flywheel than thebolts of the means for fastening or securing the first flywheel to theoutput element of a prime mover.

As also mentioned above, the energy storing elements of the at least onedamper can include or constitute coil springs. Each coil spring can havea length between approximately four and ten times the diameters of itsconvolutions. Such energy storing elements can extend in the chamberalong arcs, the sum of which would be between approximately 252° and342° if the energy storing elements were installed in their chamberend-to-end. At least one of the energy storing elements can extend alongan arc of at least 140°.

If the energy storing elements are arcuate springs (e.g., coil springsor torsion springs), they can be shaped in the manufacturing plant insuch a way that their curvature does not change at all, or does notundergo any appreciable change, during installation in or upon removalfrom the chamber.

The energy storing elements can be selected and installed in such a waythat at least one first energy storing element opposes rotation of theflywheels relative to each other with a first force and that at leastone second energy storing element opposes rotation of the flywheelsrelative to each other with a second force which is different from(namely greater or smaller than) the first force. Furthermore, theenergy storing elements can be designed and mounted in such a way thatat least one such element opposes a first stage of rotation of theflywheels relative to each other and that at least one other elementopposes a second stage of such rotation. The second stage can partiallyoverlap the first stage or can follow or precede the first stage.

If the energy storing elements are or include coil springs, theconfiguration of their convolutions can be such that the pitch of eachend convolution or at least one of the two end convolutions of each coilspring is the same or nearly the same as the pitch of each additional(intermediate) convolution of each coil spring.

A body of wear-resistant material can be installed in the chamber of theenclosure radially outwardly of the energy storing elements so that itis contacted by the energy storing elements when such elements tend tomove radially outwardly under the action of centrifugal force inresponse to rotation of the enclosure with one of the flywheels. Such abody protects the radially outer portion of the enclosure from excessivewear and its material can be selected with a view toward reducingfriction between the body and the energy storing elements in thechamber.

The apparatus can further comprise means for centering the housing ofthe friction clutch on the second flywheel.

The housing of the friction clutch can be provided with a portion (e.g.,a tubular or cylindrical portion) which extends in the direction of thecommon axis of the flywheels and at least partially surrounds the secondflywheel. Such axially-extending portion can center the housing on thesecond flywheel. Furthermore, such axially-extending portion of thehousing can be welded or otherwise bonded or affixed to the secondflywheel. It is also possible to separably couple the aforementionedportion of the housing to the second flywheel. The means for separablycoupling can include one or more discrete parts or can form part of thehousing.

The improved torque transmitting apparatus can be constructed andassembled in such a way that a radially extending portion of the clutchdisc or clutch plate is adjacent to one side of the single wall or oneof several walls of the enclosure, one side of such portion of theclutch disc is adjacent and at least substantially conforms to theoutline of the side of the wall. This entails desirable savings inspace.

One or more walls of the enclosure can be provided with openings whichafford access to the bolts of the means for fastening the first flywheelto the output element of the prime mover. The clutch disc and/or thewall or walls of the enclosure can be provided with means for deflectinga viscous or pulverulent lubricant, which at least substantially fillsthe chamber, when the lubricant tends to escape from the chamber in theregion of the clutch disc and/or the adjacent wall or walls of theenclosure.

The clutch disc can be provided with one or more openings affordingaccess to the heads of the bolts and permitting such bolts to passtherethrough for the purpose of introducing their shanks into tappedholes or bores provided in the output element of the prime mover. Inaddition to the clutch disc, one or more additional constituents of thefriction clutch (such as the housing and/or the pressure plate and/orthe clutch spring) can be provided with openings which enable theworking end of a suitable tool to reach the heads of the bolts, eitherfor the purpose of driving the shanks of the bolts into the outputelement or for the purpose of disconnecting the first flywheel from theoutput element.

The friction clutch which is used in the improved apparatus can beconstructed and assembled in such a way that the clutch spring (such asa diaphragm spring) which is installed between the housing and theaxially movable pressure plate includes a substantially washer-like mainportion and a set of prongs extending radially of the main portion,e.g., radially inwardly toward the common axis of the flywheels. Themain portion of the clutch spring bears upon the pressure plate to thusensure that the clutch disc is reliably clamped between and rotates withthe pressure plate and the counterpressure plate (the latter preferablyconstitutes or forms part of the second flywheel) in the engagedcondition of the friction clutch. The main portion of the clutch springis movable in the direction of the common axis of the flywheels towardand away from the clutch disc, and the outline of that side of the mainportion of the clutch spring which confronts the counterpressure plateis preferably selected in such a way that it is adjacent and at leastsubstantially conforms to the outline of one side of the clutch discupon movement of the main portion of the clutch disc toward thecounterpressure plate. As already mentioned above, the clutch disc canbe provided with openings, preferably adjacent the prongs of the clutchspring, which permit the bolts to pass therethrough, either towardengagement with the output element of the prime mover or duringdetachment of the first flywheel from the output element. Additionalopenings can be provided in the clutch spring in order to enable theworking end of a tool, such as a motorized screw driver, to reach theheads of the bolts.

The housing and the counterpressure plate (preferably constituting orforming part of the second flywheel) rotate as a unit when the firstflywheel is driven by the prime mover, and the pressure plate of theclutch is disposed between and is rotatable with the housing and thecounterpressure plate. The pressure plate can be provided with one ormore projections which confront the housing and are received, or arereceivable, in openings provided therefor in the clutch spring. Theopenings for the projections of the pressure plate can be disposedbetween neighboring prongs of the clutch disc, i.e., the latter can beconstructed in such a way that it includes relatively narrow slotsbetween certain neighboring prongs and wider slots (constitutingopenings for the projections of the pressure plate) between certainother neighboring prongs. For example, certain prongs can be omitted orcut away in order to provide (with the neighboring narrow slots)openings for the projections of the pressure plate.

The pressure plate is or can be axially movably connected with thehousing of the friction clutch by a set of leaf springs. In accordancewith a further feature of the invention, at least a portion of each leafspring is connected to that side of the housing which faces away fromthe pressure plate. This constitutes a radical departure from themounting of leaf springs in heretofore known friction clutches whereinthe leaf springs are connected to the pressure plate and to that side ofthe housing which confronts the pressure plate.

If the clutch spring is a diaphragm spring, that side of the housingwhich confronts the pressure plate preferably carries a ring-shaped seatassembly (e.g., two wire rings at opposite sides of the diaphragmspring) which tiltably supports the main portion of the diaphragmspring. That side of the pressure plate which faces toward the housingcan be designed to have an outline which is at least substantiallycomplementary to the outline of the seat assembly. The other side of thepressure plate is provided with the at least one friction surface orwith one of two friction surfaces; the friction surface or surfacesserve to engage the adjacent radially outer portion of the clutch discso that the latter is clamped between the pressure plate and thecounterpressure plate in the engaged condition of the friction clutch.The outline of that side of the pressure plate which faces the housingand the seat assembly can be configurated in such a way that the seatassembly is overlapped by the pressure plate in the direction of thecommon axis of the flywheels as well as radially of the common axis inthe disengaged condition of the friction clutch. All this contributes tocompactness of the friction clutch and of the entire torque transmittingapparatus.

At least one of the seats of the composite seat assembly or the singleseat of a simplified seat assembly is secured to the housing, preferablyin such a way that the means for securing the seat or seats forms partof the housing of the friction clutch. For example, the securing meanscan include prongs or lugs which are inwardly bent portions of thebottom end wall of the clutch housing. As mentioned above, that side ofthe axially movable pressure plate of the friction clutch which facesthe housing can have an outline or contour which is selected with a viewto permit the seat or seats for the main portion of the diaphragm spring(clutch spring) to be at least partially recessed into the pressureplate in the disengaged condition of the clutch.

Additional savings in space can be achieved if the single wall or one ofseveral walls of the enclosure (namely the wall adjacent the firstflywheel) is configurated in such a way that the outline of that sidewhich faces the first flywheel is complementary to the adjacent portionof the first flywheel.

At least the major portion of at least one of the flywheels,particularly the first flywheel, can consist of metallic sheet material.

A starter gear can be provided on one of the flywheels, particularly onthe first flywheel. The starter gear can comprise several (e.g., two)overlapping layers of folded metallic sheet material. Such starter gear,or a differently made starter gear, can be of one piece with one of theflywheels, particularly with the first flywheel.

In order to enhance the inertia of the first flywheel, this flywheel cancomprise a main section (e.g., of metallic sheet material) and a masswhich is connected to or is of one piece with the main section. The masscan constitute a casting or it can comprise layers of folded metallicsheet material.

The mass of the first flywheel can be configurated to at least partiallysurround the axially extending portion of the clutch housing.

The means for opposing rotation of the flywheels relative to each otheror the at least one damper can comprise a friction generating device,e.g., a slip clutch. The friction generating device can be disposedradially outwardly of the energy storing elements of the at least onedamper. The at least one friction surface of the friction clutch can bedimensioned and positioned in such a way that it includes a firstportion at a first radial distance from the common axis of the flywheel,an intermediate portion at a greater second radial distance from thecommon axis, and a third portion at a greatest radial distance from thecommon axis. The friction generating device can be installed at a fourthradial distance from the common axis of the flywheels, preferably afourth distance which matches or exceeds the second radial distance.

The friction generating device can be constructed in such a way that itcomprises at least one carrier or shoe having two friction surfacesdisposed at different radial distances from the common axis of theflywheels. The at least one shoe can be maintained in frictionalengagement with the first flywheel. Furthermore, the second flywheel caninclude a portion in frictional engagement with the at least one shoe.The at least one shoe can be dimensioned and positioned in such a waythat it has limited freedom of angular movement relative to theaforementioned portion of the second flywheel about the common axis ofthe flywheels and/or vice versa.

It is also possible to employ a friction generating device whichcomprises a plurality of shoes; the second flywheel then preferablycomprises portions, each of which engages or can engage one of theshoes. At least some of the shoes and the respective portions of thesecond flywheel are preferably movable relative to each other about thecommon axis of the flywheels with different freedoms of angularmovement.

That part of the housing or casing of the friction clutch which extendsin the direction of the common axis of the flywheels can form part ofthe friction generating device. Furthermore, the aforementioned mass ofthe first flywheel can form part of the friction generating device or ofone of several friction generating devices. If the mass of the firstflywheel and the axially extending portion of the clutch housing areparts of the friction generating device and the mass at least partiallysurrounds the axially extending portion of the housing (or vice versa),such friction generating device can include at least one shoe which isat least close to the region where the mass and the axially extendingportion of the housing overlie each other.

The friction generating device can comprise at least one energy storingelement, and such energy storing element can be stressed in a directionsubstantially radially of the common axis of the flywheels.

The at least one shoe of the friction generating device can be carriedby the first flywheel. For example, the at least one shoe can be clampedor mechanically or otherwise connected to the first flywheel indifferent ways.

If the friction generating device employs a plurality of shoes, they areor they can be spaced apart from each other in the circumferentialdirection of the flywheels.

The single shoe or each shoe of the friction generating device can havea friction generating portion of a suitable plastic material.

The clutch spring and/or the clutch disc of the friction clutch can beprovided with one or more passages for a suitable coolant, e.g.,atmospheric air. Adequate cooling of the friction clutch prolongs theuseful life of the clutch and of the entire torque transmittingapparatus. One or more passages for a coolant can also be provided inthe housing, e.g., in the aforementioned axially extending portion ofthe housing and/or in the radially extending bottom wall or end wall ofthe housing. Still further, the first and/or the second flywheel can beprovided with one or more coolant-conveying passages. The passage orpassages of the second flywheel are or can be disposed radiallyoutwardly of the chamber for the energy storing elements of the at leastone damper.

For example, the distribution of passages can be such that the secondflywheel is provided with one or more passages radially outwardly of thechamber and that the clutch disc is provided with one or more passages.Such passages serve to establish one or more paths for the flow ofcoolant through the clutch disc, along the single wall or along at leastone wall of the enclosure, through the second flywheel and toward thefirst flywheel. Alternatively or in addition to the just-mentioned pathor paths, the first flywheel can be provided with one or more passagesto establish one or more paths for the flow of coolant along the singlewall or along at least one wall of the enclosure and along the secondflywheel. The just-mentioned passage or passages of the first flywheel,or one or more additional passages of the first flywheel, are preferablydesigned to establish one or more paths for the flow of coolant throughthe first flywheel and directly or indirectly against the secondflywheel. Since the latter preferably constitutes or includes thecounterpressure plate of the friction clutch, it is heated in responseto repeated engagement and disengagement of the clutch and anyoverheating of the second flywheel could adversely affect the bearingand/or the lubricant in the chamber for the energy storing elements ofthe at least one damper.

At least one side of at least one of the flywheels is preferablyenlarged, e.g., by grooving, by the provision of protuberances or in anyother suitable way to ensure the dissipation of large amounts of heat.It is particularly desirable and advantageous to enlarge that side orsurface of the second flywheel which faces away from the clutch disc,i.e., which is located opposite the friction surface of the secondflywheel if the latter constitutes the counterpressure plate of thefriction clutch.

Analogously, that surface of the pressure plate in the friction clutchwhich faces away from the clutch disc is or can be enlarged to dissipatelarger amounts of heat. The other surface of the pressure plate is orcan constitute the friction surface or one of two friction surfaces ofthe clutch.

The friction clutch and/or the enclosure for the energy storing elementsof the at least one damper and/or at least one of the flywheels can beprovided with one or more substantially vane- or blade-like aircirculating portions.

The flywheels and the friction clutch (inclusive of the clutch disc) canbe assembled into a module which is ready to be fastened to the outputelement of a prime mover by means of the aforementioned bolts or in anyother suitable way. The bolts or other suitable fasteners can beinstalled in the module, preferably in such a way that they arenon-separably confined in the module in optimum positions for attachmentto the output element of the prime mover.

The improved apparatus can employ a push-type or a pull-type frictionclutch.

If the apparatus employs means for limiting the magnitude of torquewhich the at least one damper transmits between the flywheels, suchtorque limiting means can be mounted to be at least substantiallycoplanar with the energy storing elements of the at least one damper andwith the second flywheel.

The chamber which is defined by the aforediscussed enclosure is or canconstitute a substantially annular chamber with a radially outer portionor compartment for the energy storing elements of the at least onedamper.

The bearing can be mounted in such a way that it is at leastsubstantially coplanar with the second flywheel, with the energy storingelements of the at least one damper and with the torque limiting means.Such torque limiting means can be disposed radially outwardly of theenergy storing elements of the at least one damper and radially inwardlyof the second flywheel.

Another feature of the invention resides in the provision of a torquetransmitting apparatus which comprises: a first flywheel connectable toa rotary output element; a second flywheel which is rotatable with andrelative to the first flywheel about a common axis and is connectablewith a rotary input element by a friction clutch; means for opposingrotation of the flywheels relative to each other, including at least onedamper having energy storing means disposed, at least in part, in achamber of an enclosure; and means for limiting the magnitude of torquewhich is being transmitted from the second flywheel to the frictionclutch. The first flywheel includes a portion which transmits torquefrom the output element to the energy storing means and the enclosureincludes at least one wall receiving torque from the energy storingmeans in response to rotation of the first flywheel. The torque limitingmeans comprises at least one friction generating member (such as a brakeshoe) disposed between the enclosure and the second flywheel, at leastin part, radially outwardly of the energy storing means and, at least inpart, radially inwardly of a friction surface of the clutch.

A further feature of the invention resides in the provision of a torquetransmitting apparatus which comprises first and second flywheelsrotatable with and relative to each other about a common axis, and meansfor opposing rotation of the flywheels relative to each other includingat least one damper having at least one coil spring which has an endconvolution and at least one additional convolution. The at least onedamper further comprises an input member which is driven by one of theflywheels, which engages the end convolution and which is configuratedin such a way that it can transmit torque to the end convolution withoutappreciably changing the orientation of the end convolution relative tothe at least one additional convolution in response to rotation of theone flywheel. The at least one damper also comprises at least one outputmember which serves to transmit torque from the at least one coil springto the other flywheel in response to rotation of the one flywheel.

An additional feature of the invention resides in the provision of atorque transmitting apparatus comprising: first and second flywheelswhich are rotatable with and relative to each other about a common axis;a bearing between the flywheels; means for fastening the first flywheelto a rotary output element; and a friction clutch which serves toconnect the second flywheel with a rotary input element. The frictionclutch has an annular friction surface and the input element has aprofile which is disposed at a first radial distance from the commonaxis of the flywheels when the clutch connects the second flywheel withthe input element. The apparatus further comprises means for opposingrotation of the flywheels relative to each other, including at least onedamper having energy storing means, an input member between the firstflywheel and the energy storing means, and an output member between theenergy storing means and the second flywheel. The apparatus stillfurther comprises an enclosure which defines a chamber for a portion of,or the entire energy storing means. The bearing is disposed at a secondradial distance from the common axis of the flywheels, the fasteningmeans is disposed at a third radial distance from the common axis, afirst portion of the enclosure is disposed at a fourth radial distancefrom the common axis, the energy storing means is disposed at a fifthradial distance from the common axis, a second portion of the enclosureis disposed at a sixth radial distance from the common axis, and thefriction surface of the clutch is disposed at a seventh radial distancefrom the common axis. At least four of the first, second, . . . seventhdistances are different from each other.

A further feature of the invention resides in the provision of a torquetransmitting apparatus which comprises first and second flywheelsrotatable with and relative to each other about a common axis, and meansfor opposing rotation of the flywheels relative to each other, includingat least one damper which comprises at least one coil spring having anend convolution with a first pitch and at least one additionalconvolution having a second pitch that at least approximates the firstpitch. The at least one damper further comprises at least one inputmember which is driven by one of the flywheels and serves to transmittorque to the end convolution of the at least one coil spring withoutappreciably changing the first pitch. The at least one damper alsocomprises at least one rotary output member which serves to transmittorque from the at least one coil spring to the other flywheel inresponse to rotation of the one flywheel.

An additional feature of the invention resides in the provision of atorque transmitting apparatus comprising: an engageable anddisengageable friction clutch, including a pressure plate rotatableabout and movable in the direction of a predetermined axis; a drivencounterpressure plate (e.g., a flywheel) which is coaxial with androtates the pressure plate; and means for biasing the pressure plateaxially toward the counterpressure plate in the engaged condition of theclutch. The biasing means comprises a diaphragm spring having at leastone opening and the pressure plate has at least one projection which isreceived in the at least one opening in at least one of the engaged anddisengaged conditions of the clutch.

Another feature of the invention resides in the provision of a torquetransmitting apparatus which comprises: a friction clutch including arotary pressure plate; a rotary housing or casing coaxial with thepressure plate and having a first side confronting the pressure plateand a second side facing away from the pressure plate; and means forcoupling the pressure plate to the housing with freedom of movement inthe direction of the common axis of the housing and pressure plate. Thecoupling means comprises leaf springs; and at least a portion of eachleaf spring is disposed at the second side of the housing.

An additional feature of the invention resides in the provision of atorque transmitting apparatus which comprises first and second flywheelsrotatable with and relative to each other about a common axis, and meansfor opposing rotation of the flywheels relative to each other, includinga friction generating device which comprises at least one shoe withfirst and second friction surfaces disposed at different radialdistances from the common axis of the flywheels.

Another feature of the invention resides in the provision of a torquetransmitting apparatus which comprises first and second flywheelsrotatable with and relative to each other about a common axis, and meansfor opposing rotation of the flywheels relative to each other, includinga friction generating device and a damper having energy storing elementsinterposed between the flywheels and acting in a directioncircumferentially of the flywheels. The energy storing elements, one ofthe flywheels and the friction generating device are at least closelyadjacent a plane which is normal to the common axis of the flywheels.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved torque transmitting apparatus itself, however, both as to itsconstruction and its mode of operation, together with additionalfeatures and advantages thereof, will be best understood upon perusal ofthe following detailed description of certain presently preferredspecific embodiments with reference to the accompanying drawings,wherein:

FIG. 1 is an axial sectional view of a torque transmitting apparatuswhich embodies one form of the invention;

FIG. 2 is a fragmentary elevational view substantially as seen in thedirection of arrow II in FIG. 1;

FIG. 3 an elevational view of the energy storing elements forming partof a damper in the apparatus of FIGS. 1 and 2;

FIG. 4 is a fragmentary sectional view of a friction generating devicewhich can be utilized in the torque transmitting apparatus of thepresent invention;

FIG. 5 is a fragmentary sectional view of the friction generating devicewhich is utilized in the apparatus of FIGS. 1 and 2 and constitutes amodification of the friction generating device of FIG. 4;

FIG. 6 is a fragmentary axial sectional view of a second torquetransmitting apparatus according to the invention;

FIG. 6 a is a fragmentary sectional view of a modified clutch disc whichcan be utilized in the apparatus of FIGS. 1-2 or in the apparatus ofFIG. 6;

FIG. 7 is an axial sectional view of a third torque transmittingapparatus according to the invention;

FIG. 8 is a fragmentary axial sectional view of a fourth torquetransmitting apparatus according to the invention;

FIG. 9 is a fragmentary end elevational view of a combination of primaryflywheel and a diaphragm spring as seen in the direction of arrow IX inFIG. 8;

FIG. 10 is a fragmentary axial sectional view of a fifth torquetransmitting apparatus according to the invention;

FIG. 11 is a fragmentary sectional view substantially as seen in thedirection of arrow XI in FIG. 10;

FIG. 12 is an enlarged fragmentary sectional view substantially as seenin the direction of arrow XII in FIG. 10;

FIG. 13 is a fragmentary axial sectional view of a sixth torquetransmitting apparatus according to the invention; and

FIG. 14 is a fragmentary axial sectional view of a further torquetransmitting apparatus according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 and 2 illustrate certain details of a torque transmittingapparatus which can be installed in the power train between the primemover (e.g., an internal combustion engine or an electric motor) and thewheels of a motor vehicle. For example, the apparatus can be installedbetween the rotary output element (e.g., a camshaft or a crankshaft) ofa combustion engine and the rotary input element (e.g., a shaft) of avariable-speed transmission. Reference may be had, for example, tocommonly owned U.S. Pat. No. 4,989,710 granted Feb. 5, 1991 to Reik etal.; this patent shows an engine, the rotary output element of theengine, a transmission and the rotary input element of the transmission.

The apparatus comprises a composite flywheel 1 including a first orprimary flywheel 2 which can be separably affixed to the output elementof the prime mover, and a second or secondary flywheel 3 which isrotatable with and relative to the primary flywheel 2 about a commonaxis X—X. The secondary flywheel 3 can transmit torque to the inputelement of the transmission by way of a friction clutch 4 having aclutch disc or clutch plate 5 which is clamped between a frictionsurface 3 a of the flywheel 3 and a friction surface 55 a of an axiallymovable and rotatable pressure plate 55 of the clutch 4 when the latteris engaged, namely when the pressure plate 55 is biased axially towardthe secondary flywheel 3. The secondary flywheel 3 constitutes thecounterpressure plate of the clutch 4, and the hub 5 a of the clutchdisc 5 has an internal profile (e.g., a profile including axiallyparallel alternating internal teeth and splines) which is complementaryto and non-rotatably surrounds the external profile of the input elementof the transmission so that such input element is compelled to rotatewith the clutch disc 5 when the clutch 4 is properly engaged.

The illustrated clutch disc 5 is relatively simple in that it merelycomprises the hub 5 a and a substantially disc-shaped portion whichsurrounds and extends radially outwardly from the hub 5 a into the spacebetween the friction surfaces 3 a, 55 a of the secondary flywheel 3 andthe pressure plate 55. Reference may be had, for example, to commonlyowned U.S. Pat. No. 5,161,660 granted Nov. 10, 1992 to Huber whichdiscloses a more sophisticated clutch disc with two sets of frictionlinings disposed at opposite sides of a carrier which can transmittorque from the friction linings to the hub by one or more dampers. Itis also possible to install springs between the friction linings and therespective sides of the carrier of friction linings; such springs yieldand store energy during engagement of the clutch to thus establish aneven more reliable frictional engagement between the friction linings ofthe clutch disc 5 and the friction surfaces 3 a, 55 a of the pressureplate and the counterpressure plate.

The apparatus further comprises an antifriction or roller bearing 6which is installed between the radially inner portions of the flywheels2, 3 radially inwardly of an annulus of threaded members 8 (hereinaftercalled bolts for short) which constitute the means for separablyaffixing or securing the flywheel 2 (and hence the entire torquetransmitting apparatus) to the rotary input element of the prime mover.The illustrated bearing 6 comprises a single row of rolling elements inthe form of spheres; however, it is equally within the purview of theinvention to employ a different (e.g., a more complex) antifrictionbearing with rolling elements in the form of needles, balls, barrels orthe like. Furthermore, it is also possible to employ a composite bearingincluding for example a discrete first antifriction bearing and adiscrete second antifriction bearing which may, but need not, beidentical with the first bearing.

The bearing 6 of FIG. 1 is provided with a sealing element or cap 6 awhich confines a mass of suitable lubricant (e.g., grease) between theinner and outer races of thebearing. Furthermore, the sealing element 6a can constitute a heat barrier which prevents an excessive transfer ofheat from the secondary flywheel 3 to the bearing 6. The secondaryflywheel 3 is likely to be heated to an elevated temperature in responseto the repeated engagement and disengagement of the friction clutch 4,i.e., in response to repeated engagement of the friction surface 3 awith and in response to repeated disengagement of such friction surfacefrom the adjacent portion of the clutch disc 5.

The apparatus of FIGS. 1 and 2 further comprises means for opposingrotation of the flywheels 2 and 3 relative to each other, and suchopposing means includes a damper 9 having an annulus of energy storingelements in the form of coil springs 10. The springs 10 are confined ina radially outer annular portion or compartment 12 of acircumferentially complete chamber 11 disposed between the flywheels 2,3 and defined by an enclosure including a first wall 38 and a secondwall 46. The coil springs 10 constitute presently preferred energystoring elements of the damper 9; however, it is also possible to employother types of coil springs, torsion springs and/or other energy storingmeans without departing from the spirit of the invention.

At least a portion of the chamber 11 is filled with a solid or viscouslubricant. For example, the chamber 11 can confine the springs 10 and abody or supply of graphite powder, viscous oil, grease or the like.

The primary flywheel 2 comprises a main section or portion 13 which isor which can be made of suitable metallic sheet material in a stamping,drawing or other available machine. The main section 13 is affixed tothe output element of the prime mover (or to a part, not shown, which isdriven by the output element) by the bolts 8. This main sectioncomprises a substantially washer-like substantially radially extendingportion or part 14 having a radially inner portion secured to asubstantially flange-like input member 15 of the damper 9. Thesubstantially radially outwardly extending portion or portions 15 a ofinput member 15 are provided with openings in register with openings orholes or bores 7 in the main section 13 of the primary flywheel 2. Theopenings of portion(s) 15 a permit the externally threaded shanks of thebolts 8 to pass into and through the bores 7 and into tapped bores orholes (not shown) in the rotary output element of the prime mover.

The inner race 16 of the bearing 6 surrounds an axially extendingannular portion 15 b of the input member 15, and the outer race 17 ofthe bearing is surrounded by the adjacent portion of the secondaryflywheel 3.

The radially outer portion of the part 14 of main section 13 of theprimary flywheel 2 merges into an annular washer- or trough-like part 18which bulges in the direction of the axis X—X toward the prime mover(the latter is assumed to be disposed to the left of the main section 13of the primary flywheel 2, as viewed in FIG. 1). The part 18 merges intoan axially extending part which is folded radially of the axis X—X toconstitute a twin-layer starter gear 19 of one piece with the mainsection 13 of the primary flywheel 2. The starter gear 19 is moredistant from the prime mover than the left-most portion of the part 18,as viewed in the direction of the axis X—X. The left-hand sheet metallayer of the starter gear 19 merges into the part 18 of the main section13, and the right hand layer 20 of the gear 19 overlies and abuts theleft-hand layer and surrounds an axially parallel portion 23 of aseparately produced mass 21 affixed to the section 13 and forming partof the flywheel 2. The gear teeth of the starter gear 19 can be formedsubsequent to folding of the two layers of the part 18 in a manner asshown in FIG. 1, i.e., first radially outwardly and thereupon radiallyinwardly. The making of teeth for the starter gear 19 can be effected ina material removing machine (e.g., a milling or broaching machine) or bysimply displacing selected portions of the material of the overlappinglayers which are to form the starter gear. Thus, instead of actuallyremoving material from the layers forming part of the starter gear 19,it is possible to merely cause the material of selected portions ofthese layers to flow and to thus provide an annulus of gear teeth. Stillfurther, it is possible to make the gear teeth in a stamping machine orpress, or to resort to one or more high-energy beams (such as laserbeams) which are trained upon the material of a blank to be convertedinto the primary flywheel 2 or onto the two layers (including the layer20) of the suitably deformed radially outer part 18 of the main section13.

It is often desirable to harden the layers of the starter gear 19 and/orthe adjacent portion or portions of the primary flywheel 2. Suchlocalized or selective hardening can be carried out, for example, in aninduction hardening or in a case hardening or carburizing machine.

The mass 21 serves to increase the mass moment of inertia of the primaryflywheel 2. Such mass constitutes a ring which is made of metallic sheetmaterial and is welded or otherwise bonded, as at 27, to the part 18 ofthe primary section 13 of the flywheel 2. The illustrated mass 21 has asubstantially L-shaped cross-sectional outline and constitutes aconverted sheet metal blank originally having a washer-like shape.Reference may be had, for example, to commonly owned German patentapplication No. P 43 15 209 corresponponding to U.S. application Ser.No. 08/230,910, filed Apr. 21, 1993 which describes and shows the mannerof converting a sheet metal blank into a ring-shaped body or masssuitable for attachment to the main section 13 of the primary flywheel 2and which further discloses a suitable method of making a laminatedstarter gear. At least the relevant passages of this German patentapplication and/or of corresponding application(s) in other countriesare incorporated herein by reference.

The mass 21 comprises two substantially cylindrical overlapping portions22, 23 which actually abut each other and surround and center an axiallyparallel portion 73 of a housing or cover 60 forming part of thefriction clutch 4. The radially outer cylindrical portion 22 of the mass21 is shorter than the radially inner portion 23 and abuts the adjacentlayer 20 of the starter gear 19. The locus of abutment of the portion 22against the layer 20 is shown at 22 a. The dimensions and theconfiguration of the flywheel 2, its starter gear 19, the mass 21 andthe clutch housing 60 are or can be selected in such a way that theseparts can be readily introduced into a transmission case, not shown,e.g., into a substantially bell-shaped transmission case which confinesthe torque transmitting apparatus without touching any of its rotarycomponents.

That part of the mass 21 which extends between the portions 22 and 23has a frustoconical external surface 22 b to facilitate convenientintroduction into a transmission case. The external surface 22 a can beformed by removing some material of the mass 21 but preferably bydisplacing some material of the portion 22 and/or 23 to thus promote thehardness of the mass 21. In the embodiment of FIGS. 1 and 2, the makingof the conical surface 22 b involved a displacement of material of thesheet metal blank in a direction to increase the thickness of theradially outer portion 22.

The radially inner portion 23 of the illustrated mass 21 is surroundedby the layer 20 and in part by the other layer of the starter gear 19and extends radially inwardly (as at 23 a) to merge into one (25) of twosubstantially radially extending washer-like portions 24, 25 of the mass21. The portions 23 a and 25 of the mass 21 are adjacent and preferablyabut the right-hand side of the outer part 18 of the main section 13 ofthe primary flywheel 2. The reference character 25 a denotes in FIG. 1that part of the mass 21 which connects the radially extending portions24, 25 to each other adjacent that side of the secondary flywheel 3which faces away from the friction surface 3 a, i.e., which faces awayfrom the friction clutch 4. The radially extending portions 24, 25 ofthe mass 21 can (and in the embodiment of FIG. 1 actually do) abut eachother. The portion 24 extends radially outwardly beyond the portion 25toward but short of the axially extending portion 23. An annulus ofcircumferentially spaced apart welded seams 27 is provided in the regionof the connection 23 a between the portions 23 and 25 of the mass 21 tobond the latter to the main section 13 of the primary flywheel 2. Thewelded seams 27 are received in recesses or holes 26 which are providedin the part 18 and/or in the adjacent portion of the left-hand layer ofthe starter gear 19 in order to facilitate the making of the seams 27.

The flange-like input member 15 of the damper 9 receives torque from andis centered on the primary flywheel 2. To this end, the main section 13of the flywheel 2 is formed with an annular seat 28 which surrounds theadjacent portion of the input member 15. Alternatively, or in additionto the seat 28, the input member 15 can be centered by and at the sametime non-rotatably connected to the main section 13 of the flywheel 2 bya set of protrusions 29 forming part of the member 15 and received incomplementary recesses, holes or sockets of the main section 13. Theprotrusions 29 can be formed by displacing selected portions of theinput member 15 in the direction of the axis X—X by resorting to one ormore material displacing tools acting upon that side of the input member15 which faces away from the flywheel 2 and the prime mover.

The input member 15 can further serve to center the composite flywheel 1on the output element of the prime mover. To this end, the radiallyinner portion of the input member 15 constitutes or is connected with acentering seat 30 which can mount the composite flywheel 1 on the outputelement of the prime mover or on another part which receives torque fromand is coaxial with the output element. For example, the seat 30 can beapplied around the crankshaft of a combustion engine which drives theprimary flywheel 2 when the torque transmitting apparatus of FIGS. 1 and2 is in use.

The input member 15 comprises a portion 15 a which extends radiallyoutwardly from the seat 30 and merges into a hollow conical portiondiverging radially outwardly of the axis X—X in a direction away fromthe main section 13 of the flywheel 2. The hollow conical portion of theinput member 15 merges into a substantially radially outwardly extendingportion which is rigidly connected to the radially outer portion of asecond substantially flange-like input member 31 of the damper 9. Theconnection between the input members 15 and 31 includes a set ofprotrusions 32 which constitute displaced portions of the material ofthe member 15 extending into complementary recesses, holes or seats ofthe member 31. The radially outer portion of the input member 31 extendssubstantially radially inwardly toward the axis X—X to merge into aslightly dished portion 33 which extends away from the main section 13of the flywheel 2. The portion 33 merges into a portion 31 a whichextends in parallelism with the axis X—X toward the prime mover andmerges into a radially inwardly extending portion 31 b. The portion 31 bis adjacent the radially extending portion 15 a of the input member 15,and the portion 31 b is also provided with openings in register withsimilar openings in the portion 15 a as well as with the holes, bores oropenings 7 of the main section 13 of the flywheel 1. This renders itpossible to readily introduce the shanks of the bolts 8 through theportion 31 b of the input member 31, through the portion 15 a of theinput member 15, through the holes 7 of the main section 13 and into thetapped bores or holes of the output element of the prime mover which isto drive the flywheel 2. The right-hand side of the portion 31 b of theinput member 31 serves as an abutment or stop for the heads of the bolts8 and is contacted by such heads when the attachment of the flywheel 2to the output element of the prime mover is completed.

The radially outer portion 31 c of input member 31 defines substantiallyradially outwardly extending arms 35 which directly contact the endconvolutions of, and transmit torque to, the energy storing springs 10of the damper 9 in response to rotation of the primary flywheel 2.Analogously, the radially outer portion 15 c of the input member 15 isprovided with arms 34 which extend radially outwardly into engagementwith the adjacent outermost or end convolutions of the springs 10 in theradially outer portion or compartment 12 of the chamber 11 which isdefined by the walls 38 and 46 of the aforementioned enclosure. The arms34 are adjacent the dished portion 33 of the input member 31.

As can be best seen in FIGS. 1 and 3, the damper 9 comprises twocomposite coil springs 10 including a first spring 10 a and a secondspring 10 b which is at least substantially confined in the respectivespring 10 a. The arms 34, 35 of the input members 15, 31 extend radiallyoutwardly into the chamber 11 and into the spaces between the endconvolutions of the springs 10. These springs store energy in responseto rotation of the flywheels 2 and 3 relative to each other, i.e., thesprings 10 act in the circumferential direction of the compositeflywheel 1.

The end convolutions of each outer spring 10 a can be closely adjacent(e.g., substantially coplanar with) the end convolutions of therespective inner springs 10 b. This can be readily seen in FIG. 3 whichfurther shows that the arms 34, 35 do not exactly overlie each other.The configuration of the arms 34 and 35 is such that they need not alterthe orientation (pitch) of the adjacent end convolutions of the springs10 a and 10 b relative to the respective adjacent intermediate oradditional convolutions. This is desirable and advantageous because itis not necessary to precision finish the end convolutions of the springs10 a and 10 b, such as by removing surplus material, changing theorientation of the end convolutions and/or other treatments which arenecessary in order to finish the end convolutions of coil springs. Thearms 34, 35 which are shown in FIG. 3 can be said to constitute steppedcomposite abutments for the corresponding coil springs 10 a, 10 b toensure reliable and predictable transmission of torque from the flywheel2 to the composite springs 10 and thence to the secondary flywheel 3when the improved torque transmitting apparatus is in actual use.Otherwise stated, the configuration of those edge faces of the arms 34,35 which abut the adjacent end convolutions of the springs 10 a, 10 bare designed to conform to the orientation of such end convolutionsrather than the other way around.

The end convolutions of the springs 10 a, 10 b which are shown in FIG. 3have ends which are obtained by the simple expedient of subdividinglonger coil springs having requisite diameters into shorter sections orsprings by making cuts in planes including the axes of the longersprings. The end convolutions do not abut the neighboring intermediateor additional convolutions of the respective springs 10 a and 10 b.Thus, it is not necessary to grind or otherwise treat the ends of theend convolutions so that the treated ends will have faces located inplanes extending at right angles to the axes of the respective springs.It is also not necessary to deform the end convolutions so as to movethem into actual contact with the immediately adjacent intermediate oradditional convolutions. Otherwise stated, all convolutions of eachspring 10 a or 10 b can have an identical pitch or lead, not unlike thethreads of a bolt or another externally threaded fastener.

An advantage of the just-outlined design of the springs 10 a and 10 b isthat they can be mass-produced at a reasonable cost, as well as thatthey can undergo a more pronounced axial stressing than conventionalcoil springs with end convolutions finished and oriented in theaforedescribed conventional manner. Thus, the end convolutions of thesprings 10 a and 10 b can also yield before they actually engage theadjacent intermediate or additional convolutions so that the conversionof a spring 10 a or 10 b into a solid block with abutting convolutionsrequires a relatively large angular displacement of the flywheels 2 and3 relative to each other. The springs 10 a, 10 b do not have or need nothave any convolutions which already abut the neighboring convolutionsprior to the application of a stress in a direction to reduce the lengthof such springs. Thus, the capacity or ability of the springs to permitgreater angular displacement of the flywheels 2, 3 relative to eachother is enhanced over that of conventional coil springs by the simpleexpedients of properly configurating and mounting the arms 34, 35 of theinput members 15, 31 and by avoiding any initial deformation of the endconvolutions into actual contact with the immediately adjacentintermediate or additional convolutions. Such advantages are achieved byactually simplifying the making of the springs 10 a, 10 b, i.e., it ispossible to dispense with grinding or other treatment of the ends of endconvolutions as well as to dispense with initial changes of orientationof the end convolutions into abutment with the neighboring convolutions.

The just-described feature of configurating the arms 34, 35 and the coilsprings 10 a, 10 b can be resorted to with equal or similar advantage innumerous heretofore known torque transmitting apparatus, e.g., in thosedisclosed in the aforementioned commonly owned U.S. Pat. No. 4,989,710to Reik et al. and, therefore, such feature is deemed to warrant patentprotection with, as well as independently of, other novel features ofthe improved torque transmitting apparatus. For example, the combinationof coil springs corresponding to the springs 10 a, 10 b and inputmembers (or output members) corresponding to the members 15, 31 witharms 34 and 35 can be put to use in torque transmitting apparatusemploying a single flywheel and/or in dampers which employ coil springsforming an annulus of discrete coil springs rather than sets of two ormore coil springs which partially or completely surround each other.Furthermore, the number of discrete springs or sets of two or moresprings located one within the other can be increased to three or morewithout departing from the spirit of the invention.

It is further possible to replace the two discrete input members 15, 31with a single input member which receives torque from the flywheel 2(i.e., from the output element of a suitable prime mover) transmits thetorque to springs in a manner substantially as shown in and as describedwith reference to FIG. 3. For example, the input members 15, 31 (or asingle input member replacing the members 15, 31) can be made of asuitable sintered material or they can constitute stampings or forgings.

It is further possible to design the input members 15, 31 (or a singleinput member which replaces the members 15, 31) in such a way that thearms 34, 35 not only properly engage more or less unfinished endconvolutions of the springs 10 a, 10 b but that they also serve toprevent rotation of the springs 10 a, 10 b about their respective axes.This is often desirable and advantageous because the thus modified ordesigned arms 34, 35 ensure that the respective springs 10 a, 10 bremain in optimal angular positions as selected by the manufacturer inthe plant in which the torque transmitting apparatus is assembled. Forexample, twisting of one end of a spring 10 a or 10 b relative to theother end can result in undesirable changes of certain importantcharacteristics of such springs in actual use. Twisting could result inchanges of orientation of the end convolutions relative to theneighboring convolutions and/or in unsatisfactory contact between thearms 34, 35 and the adjacent end convolutions.

The wall 38 of the aforementioned enclosure which defines the chamber 11and its compartment 12 for the springs 10 constitutes one output memberof the damper 9. The radially outer portion of the wall 38 comprisesarms 36 a, 36 b which correspond to the arms 34, 35 and engage theneighboring end convolutions of the springs 10 a and 10 b in the sameway or in a manner analogous to that described above with reference tothe input members 15, 31 of the damper 9. The wall 46 of the enclosurealso comprises arms 37 a, 37 b which engage the adjacent endconvolutions of the springs forming part of the damper 9. The arms 36 a,36 b and 37 a, 37 b may but need not exactly overlie each other as seenin the axial direction of the flywheels 2 and 3, i.e., they can bestaggered relative to each other in the circumferential direction of theflywheels, depending on the positions of the end convolutions of theouter springs 10 a and the respective inner springs 10 b relative toeach other.

The walls 38, 46 can be made of metallic sheet material, and theradially innermost portion of the wall 38 surrounds the outer race 17 ofthe antifriction bearing 6. The radially outer portion of the wall 38 isconnected to and supports the secondary flywheel 3. The radially innerportion of the wall 38 is provided with a shoulder 39 which extends inthe direction of the axis X—X toward the main section 13 of the primaryflywheel 2 and has an inner diameter matching the outer diameter of theheat-insulating cap 6 a surrounding the outer race 17 of the bearing 6.That portion of the shoulder 39 which is more distant from the flywheel2 is of one piece with a radially inwardly extending portion 40 of thewall 38; the portion constitutes a stop and abuts the adjacent side ofthe bearing 6 so that the bearing and the wall 38 are maintained inpredetermined axial positions relative to each other. The wall 38further comprises a conical portion 41 which has a constant or nearlyconstant slope and diverges radially outwardly from the radiallyinwardly extending portion 40 in a direction away from the main section13 of the flywheel 2.

The conical portion 41 of the wall 38 has openings 42 which can receivethe heads of the bolts 8 to maintain the bolts in optimum positions forintroduction into the tapped bores or holes of the output element of theprime mover, preferably in such positions that the axes of the bolts 8are at least substantially parallel to the common axis X—X of theflywheels 2 and 3. The radially outer part of the conical portion 41merges into a curved portion 43 preferably having a substantiallyconstant radius of curvature and a concave inner side rather closelyconforming to the outlines of adjacent portions of the outer springs 10a of the damper 9. Thus, the portion 43 of wall 38 confines portions ofthe springs 10 a in the radial and axial directions of the torquetransmitting apparatus. The arcuate portion 43 of the wall 38 mergesinto a substantially radial outwardly extending portion 44 which isfixedly connected to the radially outer at least substantially radiallyextending portion 45 of the second wall 46 of the enclosure defining thechamber 11 for the energy storing elements 10 a and 10 b of the damper9. A sealing element 47 (e.g., an O-ring) is interposed between theradially outermost portion 44 of the wall 38 and the radially outermostportion 45 of the wall 46 to seal the compartment 12 of the chamber 11from the surrounding atmosphere.

The radially outer portion 45 of the wall 46 includes an inner partwhich is surrounded by the sealing element 47 and merges into a tubularor cylindrical portion extending axially and away from the main section13 of the flywheel 2 into the space which is surrounded by the adjacentportion of the wall 38. This ensures a highly satisfactory sealing ofthe radially outermost part of the compartment 12 from the surroundingatmosphere. Moreover, the just mentioned cylindrical portion of the wall46 cooperates with the adjacent portion of the wall 38 to reliablycenter such walls relative to each other. The next portion of the wall46 extends substantially radially inwardly and is configurated to snuglysurround the adjacent portions of the outer springs 10 a and tothereupon extend substantially radially inwardly into the space betweenthe main section 13 of the flywheel 2 and the input member 15 of thedamper 9.

The wall 46 further comprises a portion 48 which extends to the left (asviewed in FIG. 1) toward the prime mover which drives the flywheel 2 andserves as a retainer for a sealing element 49 here shown as a diaphragmspring which reacts against and sealingly engages the portion 48 and hasa radially inner portion bearing against the adjacent portion of theinput member 15. Thus, the diaphragm spring 49 serves to seal thecorresponding portion of the chamber 11 from the surrounding atmosphere.It is also possible to install the diaphragm spring 49 in such a waythat it reacts against the input member 15 and bears against the portion48 of the wall 46. The wall 46 and/or the input member 15 can beprovided with means (not referenced) for properly centering thediaphragm spring 49 between them.

A further sealing element 50, e.g., a diaphragm spring, is provided toseal the chamber 11 radially inwardly between the input member 31 of thedamper 9 and the wall 38 of the enclosure defining the chamber 11 andits compartment 12. The radially outer portion of the diaphragm spring50 reacts against the portion 33 of the input member 31 and its radiallyinner portion bears against the wall 38 in the region of the portion 31a of the input member 31. The diaphragm spring or sealing element 50 iscentered by a set of annularly arranged projections 51 which areprovided on the wall 38 and which are or which can be formed bydisplacing the material of selected portions of the wall 38 in adirection toward the main section 13 of the flywheel 2. The individualprojections 51 can be replaced with a circumferentially complete orcomposite rib of the wall 38. Alternatively, or in addition to centeringof the diaphragm spring 50 with the wall 38, it is also possible tocenter this diaphragm spring 50 with the input member 31 of the damper9.

The outer portions 44, 45 of the walls 38, 46 are connected to andsupport and transmit torque to the secondary flywheel 3, i.e., to thecounterpressure plate of the friction clutch 4. These outer portions 44,45 are disposed at that side of the flywheel 3 which faces away from thefriction surfaces 3 a and 55 a. This is desirable and advantageousbecause, in the event of failure of the sealing element 47, anylubricant which tends to escape from the compartment 12 of the chamber11 is directed or deflected toward the primary flywheel 2 and is thusprevented from adversely influencing the action of the friction clutch4, i.e., from reaching the friction surface 3 a and/or 55 a and/or theradially outer portion of the clutch disc 5. Thus, when engaged, theclutch 4 can continue to transmit torque from the flywheel 3 to theinput element of the transmission in an optimum manner even if some ofthe lubricant or the entire body of lubricant happens to escape from thechamber 11.

The connection between the portions 44, 45 of the walls 38, 46 and thesecondary flywheel 3 comprises a suitably shaped or corrugated sheetmetal member 52 having a radially outwardly extending portion 53 whichoverlies the right-hand side of the flywheel 3 radially inwardly of thefriction surface 3 a, and more specifically radially inwardly of thatportion of the friction surface 3 a which is disposed radially inwardlyof the adjacent set of friction linings (if any) on the radially outerportion of the clutch disc 5 between the friction surfaces 3 a and 55 a.The left-hand portion of the connecting member 53 extends throughsuitable openings (not referenced) in the radially outer portions 44 and45 of the walls 38 and 46, respectively. The connecting member 52further comprises tongues 54 which are bent radially outwardly tooverlie the left-hand side of the radially outer portion 45 of the wall46 and to thus couple the portions 44, 45 of the walls 38, 46 to eachother. At the same time, the tongues 54 secure the portions 44, 45 ofthe walls 38, 46 to the radially inner portion of the flywheel 3. Thetongues 54 are bent radially outwardly against the outer side of theportion 45 of the wall 46 when the assembly of the walls 38, 46 with thesecondary flywheel 3 is completed. Prior to deformation, the tongues 54preferably extend in parallelism with the axis X—X so that they canready advance through the aforementioned openings or slots in theradially outer portions 44, 45 of the walls 38 and 46.

The composite flywheel 1 including the flywheels 2 and 3 is preferablyassembled with the friction clutch 4 (inclusive of the clutch disc 5) toform a prefabricated module which can be readily assembled at themanufacturing plant for convenient storage or shipment to the locale ofuse and for equally convenient attachment to the output element of aprime mover which is to drive the flywheel 2. This renders it possibleto dispense with a number of operations which are necessary inconnection with the assembly, shipment and mounting of heretofore knowntorque transmitting apparatus. For example, it is no longer necessary toinsert the clutch disc 5 between the flywheel 3 and the pressure plate55 at the locale of actual use, to center the thus inserted clutch disc5 relative to the friction surfaces 3 a and 55 a, to mount the frictionclutch 4 on the flywheel 3, to center the composite flywheel 1 on theoutput element of the prime mover by a mandrel or the like, to withdrawthe centering mandrel, and to individually introduce the bolts into theholes 7 of the primary flywheel 2 prior or subsequent to extraction ofthe centering mandrel.

The bolts 8 are preferably assembled with the composite flywheel 1 andwith the clutch 4 to constitute component parts of the aforementionedmodule and to thus further simplify the task of the persons or robots incharge of affixing the primary flywheel 2 to the output element of theprime mover. This can be readily achieved by introducing the shanks ofthe bolts 8 into the holes or openings 7, the registering openings ofthe input member 15 and the registering openings of the input member 31and by dimensioning the openings 42 and 56 in such a way that theypermit the advancement of the working end of a tool (e.g., a motorizedscrew driver) into engagement with the heads of the bolts 8 but toprevent such heads from advancing through the openings 42 and/or 56. Itis further possible to insert, for example, into the holes 7, resilientor yieldable parts (not specifically shown) which reliably hold the axesof the bolts 8 in the module in parallelism with the common axis X—X ofthe flywheels 2, 3 but which yield when the heads of the bolts 8 areengaged by the working end of a tool serving to drive the shanks of thebolts into the aligned tapped bores or holes in the output element ofthe prime mover.

The openings 42 are provided in or close to the radially inner portionof the wall 38, and the openings 56 are provided close to the hub 5 a ofthe clutch disc 5 so that they are aligned with the openings 42 as wellas with the openings in the input members 15, 31 and with the openingsor holes 7 in the main section 13 of the flywheel 2. If the openings 42and/or 56 are too small to permit the heads of the bolts 8 to passtherethrough, the aforementioned resilient or yieldable parts can bedispensed with.

The clutch spring 57 is a diaphragm spring which is installed betweenthe housing 60 and the pressure plate 55 of the friction clutch 4. Theradially inwardly extending prongs 57 a extend radially inwardly fromthe circumferentially complete main portion of the clutch spring 57 andcertain slots between neighboring prongs 57 a are enlarged (e.g., byomitting certain prongs) so as to provide openings for introduction ofthe working end of a rotary tool into engagement with the heads of thebolts 8. The openings of the clutch spring 57 register with the openings56 of the clutch disc 5.

The inner side of the radially extending bottom wall or end wall 74 ofthe housing 60 carries a seat assembly which tiltably supports the mainportion of the clutch spring 57 radially outwardly of the prongs 57 a.The illustrated seat assembly comprises a ring-shaped seat 58 (e.g., awire ring) between the clutch spring 57 and the bottom wall 74, and aring-shaped seat 59 (e.g., a wire ring) at that side of the clutchspring 57 which confronts the pressure plate 55. The seats 58, 59 areheld in the illustrated positions by lugs 61 which preferably constituteportions of the bottom wall 74. Such lugs or portions 61 are bent out ofthe general plane of the bottom wall 74 and are suitably deformed toextend through the slots between the prongs 57 a of the clutch spring 57and to overlie that side of the seat 59 which faces away from the bottomwall 74. The arrangement is preferably such that the lugs 61 overlie theleft-hand side as well as the radially inner side of the seat 59 so thatthe latter is reliably held in a position of exact alignment with theseat 58, i.e., against any movement in the direction of the axis X—X aswell as against any movement radially of such axis.

The seat 58 is held in a predetermined position relative to the axis X—Xand. housing 60 by a circumferentially complete or interrupted rib orcorrugation 62 which constitutes an axially displaced portion of thebottom wall 74 of the housing 60. The interrupted rib or corrugation 62can be replaced with an even simpler centering device for the seat 59,e.g., with a relatively small number of individual projections which areapplied to or extend from the inner side of the bottom wall 74 to ensurethat the center of the seat 58 is located on the axis X—X.

As can be seen in FIG. 1, the right-hand side of the pressure plate 55is configurated in such a way that it includes a portion having anoutline which is complementary to the outline of the seats 58, 59 forthe main portion of the clutch spring 57 a. Thus, the seat 59 can extendinto a circumferentially extending groove or recess in the right-handside of the pressure plate 55, at least when the clutch 4 is disengagedand the pressure plate 55 is shifted away from the clutch disc 5, i.e.,when the pressure plate is moved axially toward the bottom wall 74 ofthe housing 60. The groove or recess in the right-hand side of thepressure plate 55 shown in FIG. 1 is dimensioned in such a way that itcan receive the seat 59 as well as the adjacent portions of the lugs 61.It is also possible to replace the illustrated groove or recess with aseries of discrete recesses each of which serves to receive the adjacentportion of a lug 61 in the disengaged condition of the friction clutch4.

The means for transmitting torque from the secondary flywheel 3 to thepressure plate 55 of the friction clutch 4 (and more specifically fromthe housing 60 to the pressure plate 55) comprises a set of leaf springs63. As can be best seen in FIG. 2, one end portion of each leaf spring63 is secured to the housing 60 by a rivet 64, and the other end of eachleaf spring is secured to the pressure plate 55 by a rivet 65. The leafsprings compel the pressure plate 55 to share all rotary movements ofthe housing 60 (i.e., of the flywheel 3) but the pressure plate is freeto move in the direction of the axis X—X to frictionally engage theclutch disc 5 (clutch 4 engaged) or to permit rotation of the clutchdisc and the flywheel 3 relative to each other (clutch disengaged). Therivets 65 are adjacent projections 66 forming part of the pressure plate55 and extending toward the axis X—X radially inwardly of the frictionsurface 55 a. The projections 66 further extend in the direction of axisX—X toward and through openings 67 which are provided therefor in theclutch spring 57 a. This renders it possible to rivet (at 64) the leafsprings 63 to that side of the bottom wall 74 of the housing 60 whichfaces away from the clutch spring 57 and pressure plate 55. This novelfeature, which contributes significantly to the compactness of thefriction clutch 4, can be embodied in the illustrated friction clutch 4as well as in numerous other types of friction clutches; therefore, suchfeature is deemed to be novel and patentable per se. Moreover, thejust-described mode of connecting the pressure plate of a frictionclutch to a flywheel (in the present instance by way of the clutchhousing 60 which rotates with the flywheel 3) can be resorted toirrespective of whether the clutch receives torque from a prime mover byway of a single flywheel or by way of a composite flywheel with one ormore dampers between them.

As can be seen in FIG. 2, the openings 67 can be formed by omitting orremoving certain prongs 57 a of the clutch spring 57, i.e., the width ofeach opening 67 can match the combined width of two relatively narrowslots 57 b plus the width of a (deleted or removed) prong 57 a. It isequally possible to form the necessary openings 67 (which permit theprojections 66 of the pressure plate 55 to pass therethrough) byincreasing the width of certain slots 57 b by removing material from oneor both neighboring prongs 57 a so that the thus increased widths ofsuch slots suffice to enable a projection 66 to extend through theclutch spring 57 a. The configuration of the clutch spring 57 can besuch that its prongs 57 a are at least substantially parallel to theadjacent portions of the carrier, which supports the friction liningsand forms part of the clutch disc 5, when the clutch 4 is disengaged.

The aforementioned openings 42 of the wall 38 and the openings 56 in theclutch disc 5 serve the aforediscussed purpose of permitting the passageof the working end of a tool into engagement with the heads of the bolts8, and preferably also the additional purpose of permitting circulationof a coolant, normally atmospheric air, in order to prevent overheatingof the secondary flywheel 3, of the body of lubricant in the chamber 11and of certain other parts of the torque transmitting apparatus (such asthe bearing 6, the primary flywheel 2 and the energy storing elements10). The cooling action is further enhanced as a result of the provisionof additional passages or channels 68 and 69 in the housing 60, passagesor channels 5 b in the clutch disc 5, passages or channels 70 in thesecondary flywheel 3, and passages or channels 71 in the main section 13of the primary flywheel 2. These passages establish paths for the flowof cooling air in order to remove heat from the flywheels 2, 3, from theinput members 15, 31, from the walls 38, 46, from the clutch disc 5 andits friction linings (if any), as well as from the housing 60, clutchspring 57 and pressure plate 55 of the clutch 4. As mentioned above,adequate cooling of the enclosure including the walls 38, 46 is ofconsiderable importance in order to avoid overheating of the body oflubricant in the chamber 11, namely to prevent undue reduction of theviscosity of a paste-like or grease-like lubricant, i.e., to prevent theheated lubricant from flowing out of the chamber 11 in the event offailure of one or more aforediscussed sealing elements between thechamber 11 and the surrounding atmosphere.

Adequate cooling of at least some constituents of the torquetransmitting apparatus is desirable on the additional ground that itcontributes to longer useful life of the entire apparatus.

Additional cooling of certain constituents of the improved apparatus canbe achieved by increasing the area of certain parts in order to permitdissipation of larger amounts of heat in actual use of the apparatus.For example, it is desirable to enlarge (at 72) the area of that side orsurface of the secondary flywheel 3 which faces away from the frictionsurfaces 3 a and 55 a, and to enlarge the area of that side or surfaceof the pressure plate 55 which faces away from the friction surfaces 3 aand 55 a. The areas of certain surfaces can be enlarged by providingthem with projections and/or recesses, by imparting thereto an undulateshape and/or in any other suitable way. Still further, it is possible toimpart to certain parts of at least some of those components, which areprovided with one or more passages, configurations which resemble theblades or vanes of a fan in order to further enhance the flow of coolantalong and against various parts of the improved torque transmittingapparatus.

The housing or cover 60 of the friction clutch 4 comprises theaforementioned bottom wall or end wall 74 and the aforementioned tubularor cylindrical portion 73 which extends in the direction of the axis X—Xand is partially surrounded by the mass 21. The portion 73 surrounds thesecondary flywheel 3 and is or can be pinned, riveted, welded and/orotherwise secured to the flywheel 3 so that the latter drives thehousing 60, the pressure plate 55 and the clutch spring 57 when itreceives torque from the damper 9. Certain additional modes ofconnecting the housing of a friction clutch to a counterpressure plate(such as a flywheel) are disclosed, for example, in the published Germanpatent application No. 41 17 584.

The tubular or cylindrical portion 73 of the housing 60 includes prongsor tongues 75 which extend beyond the flywheel 3 toward the prime moverand into a space between the radially outermost part of the disc 24 ofthe mass 21 and the inner side of the portion or layer 23 of the mass21. Such space between the parts 23 and 24 of the mass 21 accommodates afriction generating device 76 which is controlled by the tongues 75 ofthe portion 73 of housing 60. The device 76 comprises at least onefriction generating member 77 (hereinafter called brake shoe or shoe forshort) which can be of the type shown in FIG. 4 (denoted by thecharacter 177) or in FIG. 5. The shoe 77 or 177 comprises at least oneplastic part or portion 78 or 178 whose curvature matches orapproximates the curvature of the space between the portions 23 and 24of the mass 21, and the friction generating device 76 further comprisesone or more energy storing members 79 or 179 which bias the shoe 77 or177 radially outwardly. Each shoe 77 or 177 is held against movement inthe direction of the axis X—X because it extends into a suitablyprofiled portion or recess 80 provided in the portion 23 of the mass 21.The recess 80 can be bounded by a surface resembling a hollow cone andhaving a tip facing toward the prime mover. A complementary conicalrecess can be provided in the radially extending portion 24 of the mass21.

The shoe 177 of FIG. 4 is different from the shoe 77 shown in FIGS. 1and 5 in that its plastic portion 178 is stressed by an energy storingmember in the form of a piece of round wire 179 which acts not unlike aleaf spring. The plastic portion 178 is originally flat and the wire 179is straight prior to insertion between the portions 23 and 24 of themass 21. Thus, the wire 179 is caused to store energy in response toflexing to follow the curvature of the internal surface of the portion23 of the mass 21, whereby the plastic portion is stressed in the radialdirection of the flywheels 2 and 3. FIG. 4 further shows that thetongues 75 of the housing portion 73 are separated from the shoe 177between them by circumferentially extending gaps or clearances 81. Suchclearances enable the mass 21 and the housing portion 73 to turnrelative to each other through a predetermined angle before the frictiongenerating device 76 becomes effective.

It is often preferred to provide a friction generating device 76 whichemploys a plurality of shoes 77 or 177 which alternate with the tongues75 and define therewith clearances or gaps 81 having different widths(as measured in the circumferential direction of the flywheels 2 and 3).This renders it possible to cause successive or selected shoes 77 or 177to become effective or operative during different (overlapping ornon-overlapping) stages of rotation of the mass 21 and housing portion73 relative to each other. Such construction of the device 76 ensures astepped or stagewise development or increase of the friction generatingaction.

It is also possible to install the shoe or shoes 77 or 177 in such a waythat the width of the clearances 81 between the shoe or shoes and theadjacent tongues 75 is reduced to zero, i.e., that the frictiongenerating device is operative during each and every stage of rotationof the flywheel 2 and its mass 21 relative to the housing portion 73.

Still further, it is possible to employ several shoes 77 or 177 and toprovide each of the plural shoes 77 or 177 with a plastic portion 78 or178 which is capable of generating a different amount of friction, i.e.,such design of the friction generating device 76 also insures a stepwiseor stagewise development of friction between the mass 21 and the housingportion 73. Thus, the materials of plastic portions 78 on two or moreshoes 77 or of plastic portions 178 on two or more shoes 177 can bedifferent or can be treated differently so that each plastic portion orat least some of the plastic portions will ensure a stagewise orstepwise intensification of the braking action between the mass 21 andthe housing portion 73. Another mode of ensuring such stepwiseintensification of the braking action is to bias two or more shoes 77 ortwo or more shoes 177 with a different radially oriented force. Eachshoe 77 or 177 can carry a plastic portion 78 or 178 at each of itssides, i.e., at different radial distances from the axis X—X.

The sealing element 47 and/or 49 and/or 50 can be replaced with a sealother than a diaphragm spring, for example, by a labyrinth seal, withoutdeparting from the spirit of the invention.

Furthermore, the illustrated antifriction bearing 6 can be replaced witha friction (sliding) bearing or with one or more other types ofbearings.

An important advantage of the improved torque transmitting apparatus isthat the damper 9 is located radially inwardly of the friction surfaces3 a and 55 a of clutch 4. This renders it possible to reduce the radialdimensions of the apparatus without unduly reducing or withoutappreciably reducing the areas of the friction surfaces. Thus, theimproved torque transmitting apparatus can embody a friction clutchwhich can transmit large torques even though its pressure plate 55 andhousing 60 are driven by flywheels which are constructed and assembledwith one or more dampers in such a way that the dampers are disposedradially inwardly of the friction surfaces.

As will be fully described hereinafter, the bearing between theflywheels can be installed in the chamber for the energy storingelements of the damper so that a single supply of lubricant suffices toadequately lubricate the energy storing elements of the damper as wellas the rolling elements of the bearing.

Regardless of the exact nature of the bearing and irrespective of theexact location where the bearing is installed between the flywheels, itis desirable to locate the bearing radially inwardly of the energystoring elements of the damper.

The abutments or arms 36 a, 36 b of the wall 38 and/or the abutments orarms 37 a, 37 b of the wall 46 can be obtained by providing the outersides of these walls with suitably configurated depressions, e.g., in amanner as fully described and shown in commonly owned U.S. Pat. No.5,042,632 granted Aug. 27, 1991 to J{umlaut over (a)}ckel. Thedisclosure of this patent is also incorporated herein by reference.

The form-locking connection (including the sheet metal member 52)between the secondary flywheel 3 and the walls 38, 46 of the enclosuredefining the chamber 11 can be replaced with a force-locking connectionor with a connection which relies on frictional engagement between thewalls 38, 46 and the flywheel 3.

The feature that the bolts 8 can serve as a means for attaching theflywheel 2 to the output element of the prime mover as well as fornon-rotatably connecting the input members 15, 31 of the damper 9 to theflywheel 2 contributes to the simplicity and lower cost of the improvedapparatus. However, it is also possible to provide discrete fastenerswhich serve the sole purpose of securing the input members 15, 31 toeach other and/or to the main section 13 of the flywheel 2. In eitherevent, it is presently preferred to connect the input members 15, 31 tothe flywheel 2 at a location radially inwardly of the energy storingelements 10 of the damper 9.

The illustrated input members 15 and 31 have radially inner portionswhich abut each other in the regions of the heads of the bolts 8,radially outer portions which abut each other in the region of thesealing element 47, and intermediate portions which are spaced apartfrom each other in the direction of the axis X—X. Such designcontributes to the stability of the composite input member including themembers 15 and 31.

The sealing element 49 and/or 50 constitutes a frictional seal. Anadvantage of such design is that the chamber 11 can be sealed from thesurrounding atmosphere in a simple and inexpensive but reliable way.

FIG. 1 shows that the friction surface 3 a of the flywheel 3 and thechamber for energy storing elements 10 of the damper are disposed in orat least close to a common plane which is normal to the axis X—X. Thistoo, contributes to compactness of the torque transmitting apparatus.Additional savings in space (as seen in the direction of the axis X—X)are achieved by positioning the bearing 6 and the heads of the bolts 8in a common plane which is normal to the axis X—X. Moreover, and asshown in FIG. 1, it is presently preferred to assemble the torquetransmitting apparatus in such a way that the chamber 11 and the energystoring elements 10 therein are disposed between the friction surface 3a of the flywheel 3 and the heads of the bolts 8. This, too, entailssavings in space as seen in the direction of the axis X—X. Additionalsavings in space are achieved by placing the axially extending portion31 a of the input member 31 radially between the energy storing elements10 and the heads of the bolts 8, i.e., in or at the radially innerportion of the chamber 11.

The torque transmitting apparatus of FIGS. 1 and 2 is assembled in sucha way that the external profile of the input element which receivestorque from the hub 5 a of the clutch disc 5 is disposed at a firstradial distance from the axis X—X, that the bearing 6 is disposed at agreater second radial distance from such axis, that the heads of thebolts 8 are disposed at a greater third radial distance from the axisX—X, that the radially inner portion of the enclosure defining thechamber is disposed at a greater fourth radial distance from the axisX—X, that the energy storing elements 10 are located at a greater fifthradial distance from the axis, that a radially outer portion of theenclosure is located at a greater sixth radial distance from the axisX—X, and that the friction surface 3 a of the second flywheel 3 islocated at a greater seventh radial distance from the axis X—X.Substantial savings in space in the direction as well as radially of theaxis X—X can be achieved by ensuring that at least four of theaforementioned seven radial distances are adhered to in such a way thatthey differ from one another.

Otherwise stated, the diameter of the external profile of the inputelement in the hub 5 a of the clutch disc 5 should not overlap thediameter of the bearing 6, the diameter of the circle formed by theheads of the bolts 8, the diameter of the radially inner portion of theenclosure for the chamber 11, the diameter of the annulus formed by theenergy storing elements 10, the diameter of the radially outer portionof the enclosure, and the minimum diameter (or at least an intermediatediameter) of the friction surface 3 a on the flywheel 3. At least fourof the seven components having the above-enumerated diameters arepreferably located in or at least close to a plane which is normal tothe axis X—X. This too contributes to compactness of the torquetransmitting apparatus. For example, the heads of the bolts 8, thebearing 6, the energy storing elements 10 and the friction surface 3 acan be located in or at least very close to a plane which is normal tothe axis X—X.

The dimensions of the springs 10 a and/or 10 b of the damper 9 can beselected in such a way that the length of each such spring is betweenfour and ten times the diameters of its convolutions. Furthermore thelength of the springs 10 a and/or 10 b in the circumferential directionof the flywheels 2 and 3 can be such that the sum of the springs (byplacing them end-to-end) has a length of 252°-342°, i.e., betweenapproximately 70-95% (preferably between 80-90%) of a complete circle.For example, each of the illustrated springs 10 can extend along an arcof more than 140°.

It is further desirable to impart to the springs 10 an arcuate shapeprior to insertion into the compartment 12 of the chamber 11, i.e., tobend the springs 10 in such a way that their curvature need not beappreciably increased or reduced during insertion into the enclosurethat includes the walls 38 and 46,or during removal from such enclosure.

The portion 73 of the clutch housing is or can be permanently orseparably affixed to the flywheel 3. For example, the portion 73 and theflywheel 3 can be welded or otherwise bonded to each other.Alternatively, the portion 73 and the flywheel 3 can be connected toeach other by pins, threaded fasteners or rivets. Still further, it ispossible to provide a readily separable connection, for example, in amanner as disclosed in the German patent application P 42 32 320corresponding to U.S. application Ser. No. 0/125,002, filed Sep. 21,1993. This is often desirable and advantageous because the housing canbe detached in order to permit replacement of a damaged clutch disc.

The feature that the radially outer portion of the clutch disc 5 has ashape at least substantially conforming to that of the adjacent wall 38of the enclosure also contributes to the compactness of the improvedapparatus.

The provision of means for deflecting the lubricant which escapes fromthe chamber 11 in the event of damage to or other failure of the sealingelement 47, 49 and/or 50 reduces the likelihood of damage to thefriction clutch 4. Such deflecting means can be installed on or can formpart of the flywheel 2, flywheel 3, wall 38, wall 46, input member 15and/or input member 31 in the regions of the sealing elements 47, 49, 50and/or at the openings or passages in the parts which are likely to becontacted by lubricant escaping from the chamber 11.

The outline of a portion of or the entire clutch spring 57 can beselected in such a way that it at least approximates or even closelyconforms to the outline of the adjacent portion of the clutch disc 5when the parts 5 and 57 are close to each other in the engaged conditionof the clutch. The provision of openings between the prongs 57 a of thespring 57 (e.g., by enlarging some of the slots 57 b in the regions ofthe openings 56 of the clutch disc 5) enables a tool to reach the headsof the bolts 8 in the fully assembled condition of the torquetransmitting apparatus. Openings in the clutch spring 57 for the purposeof permitting the introduction of a tool into and beyond the openings 56of the clutch disc 5 can also be formed by omitting or removing selectedportions of the prongs 57 a.

The friction generating device 76 constitutes an optional but desirableand advantageous feature of the improved torque transmitting apparatus.The portion or portions 78 or 178 of its shoe(s) 77 or 177 can be madeof any one of a number of suitable plastic materials, such aspolytetrafluoroethylene, polyamide 6.6, PEEK or others.

FIG. 1 merely shows two passages 68 in the bottom wall 74 and only twopassages 69 in the axially extending portion 73 of the clutch housing60. The number of such passages can be increased to further enhance thecooling of certain constituents of the improved apparatus. In addition,it is equally possible to provide such passages only in the portion 73or only in the bottom wall 74 of the housing 60. One of the presentlypreferred modes of adequately cooling the torque transmitting apparatusis to establish one or more paths for the flow of air through the clutchdisc 5, along the wall 38, through the second flywheel 3, outwardly ofthe wall 46 and against the flywheel 2. Alternatively, or in addition tosuch path or paths, it is advisable to provide one or more paths for theflow of air through the flywheel 2, along the wall 46 and against theflywheel 3. Still further, one can establish one or more paths for theflow of air through the primary flywheel 2 (at 71) and directly againstthe secondary flywheel 3.

The aforediscussed enlargement of certain surfaces on the flywheel 3(opposite the friction surface 3 a), on the pressure plate 55 (oppositethe friction surface 55 a) and/or on one or more additional componentsof the torque transmitting apparatus can be achieved in theaforediscussed manner, i.e., by grooving, raising, undulating,roughening or otherwise treating the respective surfaces in order toenhance the dissipation of heat. For example, one can employ a circularmilling tool or an analogous tool to enlarge such surfaces. Furthermore,this enlargement of certain surfaces can be carried out in such a waythat certain portions of the surfaces resemble those of vanes or bladesin a fan or the like so that rotation of the respective parts (such as 3and 55) even further enhances the flow of cool air along theaforementioned paths for the purpose of preventing overheating of thelubricant in the chamber 11, of the friction linings (if any) of theclutch disc 5, of the flywheel 3, of the pressure plate 55, of theflywheel 2, of the energy storing elements 10 and/or others.

The friction clutch 4 of FIGS. 1 and 2 is a so-called push-type clutch,i.e., the radially innermost portions of the prongs 57 a forming part ofthe clutch spring 57 must be depressed or pulled toward the flywheels 2,3 in order to disengage the clutch. However, the invention can beembodied with equal or similar advantage in so-called pull-type frictionclutches wherein the radially innermost portions of the prongs 57 a mustbe pulled or pushed in a direction away from the pressure plate in orderto disengage the clutch.

FIG. 6 illustrates a portion of a modified torque transmittingapparatus. All such parts of the apparatus of FIG. 6 which are identicalwith or clearly analogous to the corresponding parts of the apparatusshown in FIGS. 1 and 2 are denoted by similar reference characters plus100.

The composite or split flywheel assembly 101 of the apparatus which isshown in FIG. 6 is rather similar to the composite flywheel 1 exceptthat that the bearing 106 between the flywheels 102 and 103 is afriction bearing or sliding bearing, i.e., it does not employ any balls,needles or other rolling elements. The radially inner portion 115 b ofthe input member 115 has an external shoulder which is coated with afilm or layer 106 b of friction reducing material which forms acylindrical or substantially cylindrical sleeve surrounding the portion115 b and being, in turn, surrounded by the portion 139 of the wall 138.The sleeve 106 b has a radially inwardly extending collar 106 c whichoverlies the adjacent end face of the portion 115 b. Another collar 106d at the left-hand axial end of the sleeve 106 b extends radiallyoutwardly in abutment with the adjacent end face of a portion 115 d ofthe input member 115. The portion or shoulder 139 of the wall 138 has aninternal surface which surrounds the layer or sleeve 106 b, and the end139 a of the shoulder 139 conforms to the adjacent collar 106 d of thesleeve 106 b. The just-described mounting of the sleeve 106 b betweenthe shoulder 139 and the portion 115 b ensures that the wall 138 (andhence the secondary flywheel 103 which is affixed thereto and thefriction clutch 104 which is carried by the flywheel 103) is heldagainst any undesired movement in the radial direction of the commonaxis of the flywheels 102, 103 as well as at least in one direction ofsuch axis.

The illustrated friction bearing 106 can be replaced with a compositefriction bearing having a first friction reducing part which is designedto prevent radial movements of the flywheels 102, 103 relative to eachother, and a discrete second friction reducing part which serves toprevent axial movements of the flywheel in a direction toward and/or ina direction away from the flywheel 102.

The hub 5 a of the clutch disc 5 of FIGS. 1 and 2 is riveted to theradially outer portion of such clutch disc. On the other hand, the hubof the clutch disc 105 in the apparatus of FIG. 6 is friction welded (asat 105 b) to the radially outer portion of the clutch disc 105. Thus, itis not necessary to employ separate parts (rivets or the like) toproperly connect the hub and the radially outer portion of the clutchdisc 105 to each other, it is also possible to avoid the utilization ofseparately machined rivets or other fasteners by establishing aform-locking connection between the hub and the radially outer portionof the clutch disc 5. For example, some material of the hub can bedisplaced into complementary recesses or sockets of the radially outerportion of the clutch disc 105 and/or vice versa.

FIG. 6 a shows another presently-preferred connection 105 c between thehub and the radially outer portion of a clutch disc 105. The radiallyouter portion is provided with openings 156 (only one shown) each ofwhich is surrounded by a sleeve extending through an opening of the huband being expanded at its free end so as to overlie the right-hand sideof the respective portion of the hub. In other words, the radially outerportion of the clutch disc 105 is riveted to the hub without the needfor separately produced rivets. All that is necessary is to deformcertain parts of the radially outer portion of the clutch disc 105 toform the sleeves, the sleeves are caused to pass through the respectiveopenings 156, and the fee ends of the sleeves are thereupon bentradially outwardly to constitute rivet heads. The openings 156 canfurther serve to permit the working end of a tool to reach the heads ofbolts (not shown in FIG. 6 a) and/or to permit the flow of cool air whenthe apparatus including the clutch disc 105 is in use. Another advantageof the clutch disc 105 of FIG. 6 a is that the sleeves in the openings156 reinforce the radially outer portion so that it can be made of arelatively thin sheet material.

FIG. 7 illustrates a further torque transmitting apparatus wherein allsuch parts which are identical with or clearly analogous to thecorresponding parts of the apparatus of FIGS. 1 and 2 are denoted bysimilar reference characters plus 200. The secondary flywheel 203 of thecomposite flywheel 201 is connected to the wall 246 by way of itsradially outwardly extending portion 245 which overlies the entireleft-hand side of the flywheel 203 opposite the friction surface. Theradially outermost part 245 a of the portion 245 is bent in thedirection of the common axis of the flywheels 202, 203 to overlie atleast a substantial portion of the peripheral surface of the flywheel203. The part 245 a can be said to constitute a relatively shortcylinder extending from the major part of the portion 245 in a directionaway from the flywheel 202, i.e., away from the prime mover whose outputelement is to rotate the flywheel 202. The cylindrical part 245 a issurrounded by the axially extending portion 273 of the housing 260 ofthe friction clutch. The part 245 a and the housing portion 273 arenon-rotatably connected to the secondary flywheel 203 by a set ofradially extending fasteners in the form of pins, bolts, screws or thelike.

The radially extending portion 245 of the wall 246 is further providedwith tongues 246 a which at first extend in parallelism with the commonaxis of the flywheels 202, 203 to pass through slots or holes in theradially extending portion 244 of the wall 238. The tongues 246 a arethereupon bent radially inwardly to engage the right-hand side of thewall 238 and to thus reliably secure the walls 238, 246 to each other.Though it is possible to attach separately produced tongues 246 a to theradially extending portions 245, it is preferred to make these tonguesof one piece with the wall 246. This renders it possible to dispensewith the connecting member 52 which is utilized in the torquetransmitting apparatus of FIGS. 1 and 2.

Another advantage of the apparatus of FIG. 7 is that the extent of heattransfer between the flywheel 203 and the enclosure including the walls238, 246 is reduced so that the lubricant in the chamber for the energystoring elements of the damper is less likely to be overheated.

The friction generating device 276 in the apparatus of FIG. 7 employsshoes 177 of the type shown in FIG. 4. The profiled portions 180 of theshoes 177 overlie the left-hand side of the adjacent portion 224 of themass 221. An advantage of such construction is that the radially outerface of the portion 224 of the mass 221 can remain parallel to thecommon axis of the flywheels 202 and 203. In other words, it is notnecessary to machine and/or to otherwise form the conical recesses shownat 80 in FIG. 1, i.e., the mass 221 can be made with substantial savingsin time.

FIGS. 8 and 9 show the details of a further apparatus. All such parts ofthis apparatus which are identical with or clearly analogous to thecorresponding parts of the apparatus of FIGS. 1 and 2 are denoted bysimilar reference characters plus 300.

The mass 321 of the primary flywheel 302 of the composite flywheel 301of FIG. 8 has a substantially S-shaped cross-sectional outline. Thismass confines a friction generating device 376 whose construction andmode of operation are analogous to those of the friction generatingdevice 76. The apparatus of FIGS. 8 and 9 further comprises means forlimiting the magnitude of torque which can be transmitted from theprimary flywheel 302 to the friction clutch 304, and such torquelimiting means comprises a slip clutch 381. The slip clutch 381 isinterposed between the walls 338, 346 (i.e., between the output memberof the damper including the energy storing element 310) and thesecondary flywheel 303 so that it prevents the transmission of excessivetorque from the damper to the flywheel 303 and hence to the housing andpressure plate of the clutch 304. The flywheel 303 constitutes a firstpart of the clutch 304.

The walls 338, 346 of the enclosure which defines the chamber 311 forthe energy storing elements 310 are connected to each other by a member352 in a manner similar to that described for the walls 38, 46 and themember 52 of the apparatus shown in FIGS. 1 and 2. The member 352 can besaid to constitute a second part or a portion of a second part of theclutch 304 and is supported by the first part (303) at least in theaxial direction of the clutch 304. A heat-insulating friction generatinglining 382 is installed between the secondary flywheel 303 and themember 352. The illustrated friction lining 382 has a substantiallyU-shaped cross-sectional outline with one radially outwardly extendingleg between the right-hand side of the flywheel 303 and the radiallyoutwardly extending right-hand portion of the member 352, and withanother radially outwardly extending leg of the lining disposed betweenthe left-hand side of the flywheel 303 and the wall 338. The material ofthe lining 382 is preferably selected in such a way that the lining atleast impedes the transfer of heat from the flywheel 303 to the interiorof the chamber 311.

A diaphragm spring 383 is installed between the radially extendingportion 345 of the wall 346 and the deformed tongues 354 of theconnecting member 352 and serves to bias the secondary flywheel 303, theconnecting member 352 and the portions 344, 345 of the walls 338, 346against each other in the direction of the common axis of the flywheels302 and 303. This causes the friction lining 382 of the slip clutch 381to permit rotation of the flywheels 302, 303 relative to each other assoon as the magnitude of the torque being transmitted from the flywheel302 to the energy storing elements 310 of the damper exceeds apreselected value. The portions 344,345 of the walls 338, 346 arelocated in a recess provided in a radially inner portion of thesecondary flywheel 303. This recess is dimensioned to receive theportions 344, 345 and the friction surfaces of these portions.

The magnitude of maximum torque which can be transmitted by the slipclutch 381 is preferably regulatable in such a way that it decreases inresponse to maximum angular displacement of the flywheels 302 and 303relative to each other. Thus, the flywheels 302, 303 should be capableof continuing to turn relative to each other when the slip clutch 381 isat least partially disengaged. This greatly reduces or practicallyeliminates the danger of transmission of excessive torque which couldresult in damage to or in complete destruction of certain driven parts,e.g., of a variable-speed transmission which receives torque from theclutch disc of the friction clutch 304 in the apparatus of FIGS. 8 and9.

As can be seen in FIG. 9, the diaphragm spring 383 of the slip clutch381 is provided with wing-shaped protuberances 383 a which extend towardthe prime mover and can cooperate with suitably inclined or slopingramps 313 a on the main section or portion 313 of the primary flywheel302.

When the flywheels 302, 303 are caused to turn relative to each other,the protuberances 383 a approach the ramps 313 a and/or vice versa andultimately reach the corresponding ramps. This causes the diaphragmspring 383 to move axially toward the main section 313 of the primaryflywheel 302 so that the slip clutch 381 is actuated in a sense toreduce the maximum torque that can be transmitted to the secondaryflywheel 303. In other words, the slip clutch 381 is activated in asense to permit the transmission of a smaller or relatively smalltorque, i.e., the flywheel 303 and the clutch 304 which is carried byand rotates with the flywheel 303 is no longer rotated by the walls 338,346 when the magnitude of torque transmitted by the springs 310 to thewalls 338, 346 is less (or even much less) than the maximum value, suchas is being transmitted when the wings or projections 383 a are spacedapart from the ramps 313 a on the main section 313 of the primaryflywheel 302.

The slip clutch 381 can be designed in such a way that it becomeseffective only when the flywheels 302, 303 rotate relative to each otherin a single direction or that it becomes effective irrespective of thedirection of rotation of the flywheels relative to one another. Stillfurther, the slip clutch 381 can be designed in such a way that it cantransmit a relatively small torque when the two flywheels tend to rotaterelative to each other in a first direction but that it can transmit adifferent (e.g., larger) torque in response to a tendency of the twoflywheels to rotate relative to each other in a second direction counterto the first direction.

The illustrated slip clutch 381 is designed in such a way (known as endangle regulation) that it is installed at the secondary side and betweenthe secondary flywheel 303 and the energy storing elements 310, as seenin a direction radially of the common axis of the flywheels 302 and 303.The slip clutch 381 is disposed radially between the secondary flywheel303 and the energy storing elements 310 in the chamber 311, and thebearing between the two flywheels is disposed in a common plane with theheads of the bolts which are used to affix the primary flywheel 302 tothe output element of a prime mover. The bearing and the heads of thebolts are in line or substantially in line (i.e., in or close to acommon plane) with the slip clutch 381.

FIG. 10 shows a portion of a different torque transmitting apparatus.All such parts of this apparatus which are identical with or clearlyanalogous to corresponding parts of the apparatus shown in FIGS. 1 and 2are denoted by similar reference characters plus 400. The compositeflywheel 401 comprises a primary flywheel 402 and a coaxial secondaryflywheel 403. The input members 415 and 431 of the damper including theenergy storing elements 410 in the chamber 411 are configurated anddimensioned in such a way that the entire member 431 abuts the member415. In other words, not only the radially outermost and the radiallyinner portions of the input members 415 and 431 abut each other but theentire intermediate portion of the member 431 also abuts the adjacentpart of the member 415. The latter carries a centering member 430 whichcan center the primary flywheel 302, and hence the entire torquetransmitting apparatus of FIG. 10, on the output element of the primemover.

The two discrete input members 415, 431 can be replaced with a one-pieceinput member, and such one-piece input member can constitute a casting,a forging or a part made of sintered material.

The radially inner portion of the chamber 411 is bounded by a discretewall 484, i.e., the enclosure defining the chamber 411 includes threewalls 438, 446 and 484. The wall 484 is or can be made of a plasticmaterial and its radially inner portion is configurated in such a waythat it surrounds the heads of the bolts 408. This reduces thelikelihood of misorientation of the bolts 408 during storage and/orduring transport to the locale of use as well as during introduction ofthe shanks of bolts 408 into the tapped bores or holes of the outputelement of the prime mover or of a part which is driven by such outputelement.

The radially outer (right-hand) portion of the wall 484 partiallysurrounds a sealing element in the form of a diaphragm spring 450 whichcooperates with the wall 438 to seal the respective portion of thechamber 411.

The wall 438 is provided with openings 442 which permit the introductionof the bolts 408 until the heads of the bolts reach the input member431; at such time, the heads of the bolts are fully received in thesurrounding portions of the wall 484. The openings 442 are surrounded bycollars 422 a forming part of the wall 438 and extending toward theheads of the properly inserted bolts 408. Such openings not only serveto permit the introduction of bolts 408 but also enable the working endof a tool to reach and rotate the heads of the bolts for the purpose ofaffixing the primary flywheel 402 to, or of detaching the flywheel 402from, the output element of a prime mover. The collars 422 a surroundand maintain in proper orientation the heads of the bolts 408 duringtransport or at any time when the shanks of the bolts do not extend, ordo not appreciably extend, beyond the left-hand side of the main section413 of the primary flywheel 402. Still further, the collars 422 a cantogether constitute a means for centering a sealing element, e.g., asealing element which replaces the sealing element 450. In addition tobeing centered at the inner side of the wall 438, the sealing element450 can also be centered by the ring which is formed by the radiallyoutermost portions of the collars 442 a.

The axially extending portion 473 of the clutch housing 460 is connectedwith the secondary flywheel 403 by a set of plate-like members 485 whichare spaced apart from each other in the circumferential direction of theflywheels. As can be seen in FIG. 11, each plate-like connecting member485 is provided with at least one radial projection extending throughsuitable slots or cutouts or openings of the housing portion 473.Threaded fasteners 485 a are utilized to secure the connecting members485 to the secondary flywheel 403, and more specifically to that side ofthe flywheel 403 which faces away from the friction surface. The headsof the fasteners 485 a can be reached through ventilating passages orchannels 485 b which are provided in the substantially plate-like ordisc-shaped main section 413 of the primary flywheel 402. The number ofpassages 485 b can exceed the number of fasteners 485 a. FIG. 10 showsadditional passages or channels 471 and 471 a which are provided in themain section 413 of the primary flywheel to establish paths for the flowof a coolant (air) against the enclosure defining the chamber 411 aswell as directly against that side of the secondary flywheel 403 whichfaces away from the friction surfaces. The radially inner passages 471 aare positioned to direct the coolant directly against the wall 446,i.e., against the enclosure, and the radially outer passages 471 directstreams of coolant directly against the secondary flywheel 403. Such amode of cooling has been found to reliably prevent overheating of thesecondary flywheel 403 as well as of the lubricant in the chamber 411.

That portion of the right-hand side or inner side of the main section413 of the primary flywheel 402 which is adjacent the chamber 411 ispreferably configurated in such a way that it closely conforms to and isclosely adjacent the outer side of the wall 446.

FIG. 12 shows, by way of example, one presently preferred form ofabutments 436 a 436 b for the adjacent end convolutions of coil springs410 b, 410 a forming part of the energy storing elements 410 in thechamber 411. The abutments 437 a, 437 b of the wall 446 are or can bemirror images of the abutments 436 a, 436 b. Each abutment 436 bconstitutes a portion of the wall 438 which is depressed from the outerside of the wall into the chamber 411 so that it can engage the adjacentend convolutions of two outer coil springs 410 a. Each abutment 436 aconstitutes a suitably depressed part of the respective depressedportion 436 b so that it can be engaged by the end convolutions of twoadjacent inner coil springs 410 b. An advantage of such abutments orstops for the springs 410 a, 410 b is that it is not necessary toutilize separately produced parts to serve as arms which receive torquefrom the energy storing elements 410 for transmission to the secondaryflywheel 403. The abutments 436 a, 436 b can be formed simultaneouslywith the conversion of a sheet metal blank into the wall 438, i.e., theycan be formed by repeatedly deforming selected portions of the blank toform the abutments 436 b and immediately thereafter the abutments 436 a.

If the torque transmitting apparatus of FIG. 10 is installed in thepower train between the combustion engine or electric motor and thewheels of a motor vehicle, it can be provided with one or more frictiongenerating devices, e.g., one for operation while the prime mover isidling and another to be used when the prime mover drives the vehicle.

The outline of the radially outer portion of the clutch disc 405 atleast substantially conforms to the outline of the adjacent portion ofthe wall 438, and such radially outer portion of the clutch disc 405 isprovided with a number of passages, some at the radial level of thechamber 411 and some radially inwardly of the chamber. This enablesstreams of a coolant to flow along the wall 438 toward and through thepassages 470 of the secondary flywheel 403 toward and through the mainsection 413 of the primary flywheel 402.

In at least some of the illustrated embodiments of the invention,diaphragm springs which serve as a means for sealing the chamber for theenergy storing elements of the damper can further constitute componentparts of one or more slip clutches or analogous means for limiting themagnitude of transmitted torque. This enhances the versatility of theapparatus without increasing the cost because the sealing elements forthe chamber can perform the additional function of constitutingcomponent parts of one or more slip clutches or analogous torquelimiting means.

Referring to FIG. 13 , there is shown a further torque transmittingapparatus including a composite flywheel 501 composed of a primaryflywheel 502 and a secondary flywheel. All such parts of this apparatuswhich are identical with or clearly analogous to the corresponding partsof the apparatus of FIGS. 1 and 2 are denoted by similar referencecharacters plus 500. The input member 515 replaces the input members415, 431 and the wall 484. This one-piece input member can constitute acasting, a forging or a sintered part without any, or without anyappreciable, secondary treatment. This entails considerable savings inconnection with the making of the apparatus because the primary flywheel502 can be mounted on or assembled with the input member 515 in a simpleand time saving manner. A sintered input member 515 exhibits severaladditional advantages, especially as concerns the cost of making andassembling the torque transmitting apparatus. Thus, it is possible todispense with the making of a discrete wall 484 from a plastic material,and the axially extending radially inner portion 515 b can be surroundedby the inner race of the antifriction bearing 506 without any secondarytreatment. The same holds true for the centering member 530 whichcenters the primary flywheel 502 relative the secondary flywheel andrelative to the enclosure for the chamber which receives the energystoring elements of the damper.

FIG. 14 shows another torque transmitting apparatus which embodiesnumerous features of the invention. All such parts of this apparatuswhich are identical with or clearly analogous to the corresponding partsof the apparatus of FIGS. 1 and 2 are denoted by similar referencecharacters plus 600.

The composite flywheel 601 comprises a primary flywheel 602 and asecondary flywheel 603 which is coaxial with the primary flywheel 602and which can rotate together with, as well as relative to, the primaryflywheel. The secondary flywheel 603 carries a friction clutch 604having a clutch disc 605 which is interposed between the frictionsurface of the flywheel 603 and the friction surface of a pressure plate655 forming part of the clutch 604. The main section 613 of the primaryflywheel is connectable to the rotary output element of a prime mover,e.g., an engine or motor in a motor vehicle, and the hub of the clutchdisc 605 can transmit torque to the rotary input element of avariable-speed transmission in the vehicle. FIG. 14 shows a simpleclutch disc 605 because the exact construction of this part of thefriction clutch forms no part of the present invention. In actual use ofthe torque transmitting apparatus, the friction clutch 604 can embody aclutch disc of the type described and shown, for example, in theaforementioned U.S. Pat. No. 5,161,660 to Huber. As a rule, the carrierwhich extends radially outwardly from the hub of the clutch disc 605will support two sets of friction linings one of which can be engaged bythe friction surface of the secondary flywheel 603 (this flywheelconstitutes the counterpressure plate of the friction clutch) and theother of which can be engaged by the friction surface of the axiallymovable pressure plate 655 when the clutch 604 is set to transmit torquefrom the flywheel 603 to the input element of the transmission.

An antifriction bearing 606 is installed between the flywheels 602, 603by way of parts which are rigid with the two flywheels. In contrast tothe construction which is shown in FIGS. 1 and 2, the apparatus of FIG.14 is constructed and assembled in such a way that the bearing 606 islocated radially outwardly of the holes or bores 607 for the shanks ofthe bolts 608. The damper 609 includes energy storing elements 610 in achamber 611 which is defined by an enclosure including walls 638 and646. As already described with reference to FIGS. 1 and 2, and as bestshown in FIG. 3, each energy storing element 610 can comprise at leastone coil spring. Such coil springs are confined in the ring-shapedradially outermost part or compartment 612 of the chamber 611. Again,the chamber 611 is at least partially filled with a flowable solidlubricant (such as graphite powder) or with a viscous lubricant,preferably a lubricant of pasty consistency.

The main section 613 of the primary flywheel 602 is a converted blank ofmetallic sheet material. The conversion can be made in a suitablestamping, drawing or other machine in a manner not forming part of thepresent invention. The holes 607 are provided in the main section 613,and more particularly in a radially inner portion 614 of the section 613. The portion 614 is a flat washer-like part of the main section 613 andcarries an input member 615 forming part of the damper 609. The radiallyoutwardly extending portion or portions 615 a of the input member 615are provided with openings which register with the holes 607 and permitthe insertion of the shanks of bolts 608 so that the shanks can bedriven into the tapped bores of an output element, such as a crankshaftor a camshaft. The outer race 617 of the bearing 606 (which is shown inthe form of a simple ball bearing with a single annulus of rollingelements) is surrounded by an axially extending portion 615 b of onepiece with the radially extending portion(s) 615 a of the input member615. The portion 615 b can directly surround the outer race 617 or aheat barrier corresponding to the part 6 a in the apparatus of FIGS. 1and 2. The inner race 616 of the bearing 606 surrounds the adjacentportion of the secondary flywheel 603.

The radially outer part of the main section 613 includes a dishedportion 618 which extends from the plane of the portion 614 toward theprime mover (not shown) assumed to be located to the left of the primaryflywheel 602. The portion 618 is of one piece with a starter gear 619which is or which can be similar to the starter gear 19 in the apparatusof FIGS. 1 and 2. The method of making the starter gear 619 is analogousto or identical with the aforedescribed method of making the startergear 19. The radially inwardly extending portion or layer 620 of thestarter gear 619 is welded or otherwise bonded or affixed to the mainsection 613 at the inner side of the portion 618, and the portion 620 isof one piece with a further portion 620 a extending in parallel with theaxis X—X in a direction away from the prime mover, i.e., in a directiontoward the radially outermost portion of the housing or casing 660forming part of the friction clutch 604. The rightmost part of theaxially extending portion 620 a is of one piece with a radially inwardlyextending portion 620 b which is recessed into the adjacent radiallyouter portion of the mass 621 forming part of the primary flywheel 602.

The mass 621 constitutes an optional but desirable element whichenhances the moment of inertia of the primary flywheel 602. Theillustrated mass 621 is a casting and at least a substantial part of itsleft-hand side abuts the adjacent part of the main section 613 of theprimary flywheel 602. The peripheral surface of the mass 621 abuts theinternal surface of the portion 620 a between the radially inwardlyextending portion 620 b and the welded joint between the layer 620 ofthe starter gear 619 and the portion 618 of the main section 613. Thedriving connection between the main section 613 and the mass 621 isestablished by the portion 620 b which can include an annularly arrangedset of prongs of one piece with the cylindrical portion 620 a and beingbent radially inwardly into complementary recesses of the mass 621 whenthe insertion of the mass into the portion 620 a is completed. It isalso possible to avoid the making of prongs and to simply bend theentire right-hand marginal part of the portion 620 a radially inwardlyto thus reliably secure the mass 621 to the main section 613 of theprimary flywheel 602.

The input member 615 is centered relative to the primary flywheel 602,for example, by a seat 628 which extends into the centrally locatedopening of the main section 613 and abuts the radially innermost part ofthe portion 614 forming part of the main section 613. The internalsurface 630 of the input member 615 serves to center the flywheelassembly 601 and the friction clutch 604 on the output element of theprime mover.

The outer part of the radially extending portion 615 a of the inputmember 615 merges into an axially extending portion which extends alongand beyond the heads of the bolts 608 and merges into a radiallyoutwardly extending portion 615 c. This radially outwardly extendingportion constitutes a holder of or support for a set of radiallyoutwardly extending arms or abutments 634 disposed between the endconvolutions of the neighboring springs 610 in the compartment 612 ofthe chamber 611. The springs 610 act in the circumferential direction ofthe composite flywheel 601, the same as the springs 10 of the damper 9in the apparatus of FIGS. 1 and 2. Furthermore, the arms 634 can bedesigned in the same way as described in connection with the arms 34, 35which are shown in FIGS. 1 and 3, i.e., the edge faces of the arms 634can conform to the outlines of the adjacent end convolutions to avoidany misorientation of the end convolutions relative to the adjacentintermediate or additional convolutions of the springs 610.

The end convolutions of the springs 610 further bear against abutments636 and 637 which can be made, configurated and inserted in the same wayas described for abutments 36 a, 36 b and 37 a, 37 b in the apparatus ofFIGS. 1 and 2. The arms 636 are of one piece with wall 638, and the arms637 are of one piece with wall 646. The radially inner portion of thewall 638 is surrounded by the inner race 616 of the antifriction bearing606, and the radially outer portion of the wall 638 carries thesecondary flywheel 603. The inner race 616 of the bearing 606 directlysurrounds a shoulder 639 which is provided on the radially inner portionof the wall 638 and extends toward the portion 614 of the main section613 of the primary flywheel 602. The radially innermost portion 641 ofthe wall 638 is located in a plane which is at least substantiallynormal to the axis X—X, and such radially innermost portion 641 extendsfrom the inner race 616 of the bearing toward but short of the hub ofthe clutch disc 605. The portion 641 of the wall 638 is provided withopenings 642 which establish paths for the introduction of the bolts 608as well as for the working end of a tool which is to engage the heads ofthe bolts. The diameters of the openings 642 are preferably dimensionedin such a way that the openings 642 can receive the heads of the bolts608 and can properly orient such bolts when the shanks do not extend, ordo not appreciably extend, beyond the left-hand side of the main section613. Such situation can develop during storage, transport and initialstage of mounting of the torque transmitting apparatus.

An intermediate portion of the wall 638 is closely adjacent the energystoring elements or springs 610 in the chamber 611 and the configurationof such intermediate portion is such that the curvature of its left-handside matches the curvature of the adjacent portions of convolutions ofthe springs 610. The radially outermost portion 644 of the wall 638extends at least substantially radially outwardly and is connected to aradially outer portion 645 of a second wall 646. The wall 646 isinstalled between the main section 613 of the primary flywheel 602 andthe wall 638 radially inwardly of the mass 621, and its radiallyoutermost portion is welded, otherwise bonded or separably secured tothe radially outermost portion 644 of the wall 638.

A wear-resistant arcuate trough-shaped insert 612 a is installed in theradially outermost portion of the compartment 612 to prevent directcontact of the radially outermost portions of convolutions forming partof the springs 610 with the walls 638, 646 when the springs 610 orbitand tend to move radially outwardly under the action of centrifugalforce. The concave inner side of the insert 612 a can closely follow theoutlines of the adjacent portions of the springs 610.

The radially outer portion 644 of the wall 638 extends radiallyoutwardly beyond the radially outermost portion 645 of the wall 646 andis folded over itself to form a radially inwardly extending leg 644 a.The outer part of the leg 644 a directly abuts the adjacent part of theportion 644 but the inner part of the leg 644 a is spaced apart from theadjacent part of the portion 644. The radially innermost portion of theleg 644 a is located slightly radially outwardly of the compartment 612of the chamber 611. The clearance between the radially inner portion ofthe leg 644 a and the adjacent part of the portion 644 establishes apath for the circulation of air which can flow through passages 644 b inthe left-hand part of the portion 644 and thereupon radially outwardlybetween the mass 621 of the primary flywheel 602 and the secondaryflywheel 603.

The radially inner portion 648 of the wall 646 extends in parallelismwith the axis X—X toward the prime mover and serves as a retainer for asealing element in the form of a diaphragm spring 649. The latter reactsagainst the wall portion 648 and bears against the adjacent portion ofthe input member 615 to seal the neighboring portion of the chamber 611from the atmosphere. The installation of the diaphragm spring 649 can bechanged, i.e., the spring can react against the input member 615 to bearagainst the portion 648 of the wall 646. This diaphragm spring can becentered by the wall 646 and/or by the input member 615.

Another sealing element in the form of a diaphragm spring 650 isinstalled between the input member 615 and the wall 638 to seal thechamber 611 in a region adjacent and located radially inwardly of thebearing 606. The radially outer portion of the diaphragm spring 650 iscentered by and reacts against the input member 615, and the radiallyinner portion of this spring bears against the wall 638.

An advantage of the torque transmitting apparatus which is shown in FIG.14 is that the bearing 606 is located in the chamber 611 so that one andthe same supply of solid or viscous lubricant can be used to lubricatethe springs 610 as well as the rolling elements of the bearing 606, atleast when the flywheel 602 is driven by a prime mover.

The composite flywheel 601 is preferably assembled with the clutch 604(including the clutch disc 605) in the manufacturing plant to constitutea module which can be readily manipulated in storage, during shipmentand during attachment to the output element of a prime mover. Centeringof the clutch disc 605 between the friction surface of the secondaryflywheel 603 and the pressure plate 655 is preferably completed in themanufacturing plant.

The inner side of the bottom wall of the clutch housing 660 carries twoseats 658, 659 disposed at opposite sides of the circumferentiallycomplete radially outer or main portion of the clutch spring 657. Thelatter is a diaphragm spring and its main portion carries a set ofradially inwardly extending prongs. The seats 658, 659 form part of awear compensating unit 686 which is or which can be constructed,assembled and operated in a manner as disclosed, for example, in thecommonly owned published German patent application No. 42 39 291 and inthe corresponding patents and patent applications in countries otherthan Federal Republic Germany. The purpose of the unit 686 is toautomatically compensate for wear upon the friction linings of theclutch disc 605 and preferably also for wear upon the clutch spring 657,pressure plate 655 and flywheel 603.

The pressure plate 655 of the friction clutch 604 is non-rotatably butaxially movably connected to the housing 660 by a set of leaf springs663 each of which has a first end portion riveted or otherwise affixedto the housing 660 and another end portion secured to the pressure plate655 by rivets 665. The rivets 665 are located radially inwardly of thefriction surfaces of the flywheel 603 and the pressure plate 655 andradially outwardly of the location 666 a where the radially outermostportion of the clutch spring 657 bears upon the right-hand side of thepressure plate 655.

The housing 660 of the friction clutch 604, the clutch disc 605, theprimary flywheel 602 and, if necessary, certain other parts of thetorque transmitting apparatus are provided with channels or passages toensure adequate cooling of the secondary flywheel 603 and the enclosureincluding the walls 638 and 646. The distribution of such passages is orcan be analogous to that previously described with reference to FIGS. 1to 13.

The radially outer portion of the secondary flywheel 603 isnon-rotatably connected with the adjacent radially outer portion of thehousing 660. Alternatively, or in addition to such connection, thehousing can be connected with the radially outer portion 644 of the wall638 because this wall shares the angular movements of the flywheel 603.The illustrated connection includes tongues 647 a which are parallel tothe axis X—X during assembly of the module including the compositeflywheel 601 and the friction clutch 604 and are thereupon bent radiallyinwardly upon completed insertion of the secondary flywheel 603 into thehousing 660. Each tongue 647 a extends into a complementary recess orsocket in the left-hand side of the flywheel 603. This ensures that thehousing 660 and the flywheel 603 are held against axial and/or angularmovements relative to each other.

The improved torque transmitting apparatus, its flywheel assembly andits friction clutch are susceptible of numerous additional modificationswithout departing from the spirit of the invention. For example, some orall of the features shown in FIGS. 1 and 2 can be incorporated in theapparatus of FIG. 6, 7, 9, 10, 13 and/or 14 or vice versa. Furthermore,numerous features can be incorporated into certain other apparatusincluding those which are described in the references listed in thisspecification. Applicants reserve the right to seek protection for allsuch features and combinations of features in addition to those recitedin the appended claims.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of the prior art, fairly constitute essentialcharacteristics of the generic and specific aspects of theaforedescribed contribution to the art and, therefore, such adaptationsshould and are intended to be comprehended within the meaning and rangeof equivalence of the appended claims.

What is claimed is:
 1. Apparatus for transmitting torque comprising: a first flywheel connectable with a rotary output element of a prime mover; a second flywheel rotatable with as well as relative to said first flywheel about a common axis and provided with at least one friction surface disposed at a first radial distance from said axis, said second flywheel being connectable with a rotary input element of a transmission by a friction clutch; a bearing interposed between said flywheels; means for opposing rotation of said flywheels relative to each other including at least one damper having at least two energy storing elements disposed at a lesser second radial distance from said axis, said at least two energy storing elements being at least partially confined in said second flywheel and said second flywheel including a portion disposed radially outwardly of said at least two energy storing elements and extending in the direction of said axis; and means for jointly fastening said flywheels to the rotary output element of the prime mover radially inwardly of said at least two energy storing elements.
 2. The apparatus of claim 1, wherein said at least two energy storing elements have first portions disposed at a greater distance and second portion disposed at a lesser distance from said axis, at least said first portion of said at least two energy storing elements being at least partially confined in an at least substantially sealed chamber.
 3. The apparatus of claim 2, wherein said chamber is bounded by a surface including a portion conforming to and adjacent said first portions of said at least two energy storing elements.
 4. The apparatus of claim 1, further comprising an enclosure defining an at least partially sealed chamber for portions at least of said at least two energy storing elements, said enclosure having at least two walls and at least one of said walls being connected with said second flywheel.
 5. The apparatus of claim 4, wherein said at least one wall supports said second flywheel.
 6. The apparatus of claim 1, wherein said bearing includes a friction bearing.
 7. The apparatus of claim 1, wherein said bearing includes an antifriction bearing.
 8. The apparatus of claim 1, wherein at least one of said at least two energy storing elements includes at least one coil spring.
 9. The apparatus of claim 1, wherein at least one of said at least two energy storing elements includes at least one torsion spring.
 10. The apparatus of claim 1, further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure having a radially outer portion disposed at a greater distance and a radially inner portion disposed at a lesser distance from said axis, said radially inner portion being at least substantially sealed and further comprising a supply of dry lubricant at least partially filling said chamber.
 11. The apparatus of claim 1, further comprising an at least substantially sealed chamber for portions at least of said at least two energy storing elements, and means for sealing said chamber from the atmosphere, including at least one labyrinth seal.
 12. The apparatus of claim 1, further comprising a supply of viscous fluid at least partially filling an at least substantially sealed chamber for portions at least of said at least two energy storing elements.
 13. The apparatus of claim 12, wherein said viscous fluid is a paste.
 14. The apparatus of claim 1, wherein at least a portion of said bearing in disposed in an at least substantially sealed chamber for portions at least of said at least two energy storing elements.
 15. The apparatus of claim 1, wherein said bearing is disposed at a third radial distance from said axis radially inwardly of said energy storing elements.
 16. The apparatus of claim 1, further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure comprising a first wall and a second wall connected to said first wall radially outwardly of said at least two energy storing elements.
 17. The apparatus of claim 16, further comprising at least one sealing element between said walls radially outwardly of said energy storing elements.
 18. The apparatus of claim 17, wherein said at least one sealing element includes an O-ring.
 19. The apparatus of claim 1, further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including at least one wall having abutments for said at least two energy storing elements.
 20. The apparatus of claim 19, wherein said abutments include pairs of confronting depressions provided in said at least one wall and extending substantially in the direction of said axis, into said chamber, and between said at least two energy storing elements.
 21. The apparatus of claim 1, further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including at least one wall connected with said second flywheel and rotatable relative to said first flywheel.
 22. The apparatus of claim 21, wherein said second flywheel has a side facing away from said at least one friction surface and said at least one wall is disposed at said side of said second flywheel.
 23. The apparatus of claim 1, further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including at least one wall and a form-locking connection between said at least one wall and said second flywheel.
 24. The apparatus of claim 1, further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including at least one wall in frictional engagement with said second flywheel.
 25. The apparatus of claim 1, wherein said first flywheel includes a portion which transmits torque from the prime mover to said at least two energy storing elements, and further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including at least one wall receiving torque from said at least two energy storing elements and means for limiting the magnitude of torque which is being transmitted from said second flywheel to said friction clutch, said limiting means comprising at least one friction generating member disposed between said enclosure and said second flywheel at least partially radially outwardly of said at least two energy storing elements and at least partially radially inwardly of said at least one friction surface.
 26. The apparatus of claim 25, wherein said limiting means further comprises means for biasing said second flywheel and said enclosure against said at least one friction generating member.
 27. The apparatus of claim 26, wherein said biasing means includes at least one diaphragm spring.
 28. The apparatus of claim 25, further comprising biasing means actuatable to urge said second flywheel and said enclosure against said at least one friction generating member.
 29. The apparatus of claim 28, further comprising means for actuating said biasing means, said actuating means being operable by said first flywheel.
 30. The apparatus of claim 29, wherein at least a portion of said actuating means is of one piece with said first flywheel.
 31. The apparatus of claim 1, further comprising an enclosure receiving torque from said first flywheel by way of said at least two energy storing elements and defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, and friction generating torque transmitting means interposed between said enclosure and said second flywheel to transmit torque from said at least two energy storing elements to said friction clutch by way of said second flywheel.
 32. The apparatus of claim 31, wherein said friction generating means contains a heat insulating material.
 33. The apparatus of claim 1, further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including at least one wall mounted on said bearing.
 34. The apparatus of claim 1, wherein said at least one damper further comprises at least one flange having at least one portion extending into an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said at least one flange being arranged to transmit torque to said at least two energy storing elements in response to rotation of said first flywheel, said at least one flange being connected with said first flywheel radially inwardly of said at least two energy storing elements.
 35. The apparatus of claim 1, wherein said means for fastening is operative to secure said at least one flange to said first flywheel.
 36. The apparatus of claim 1, wherein said at least one damper further comprises a plurality of flanges having radially outer portions connected to each other, at least one of said flanges comprising at least one arm extending into an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said arm being arranged to transmit torque to said at least two energy storing elements in response to rotation of said first flywheel, at least one of said flanges being connected with said first flywheel radially inwardly of said at least two energy storing elements.
 37. The apparatus of claim 1, wherein said at least one damper further comprises a plurality of flanges connected to said first flywheel and at least one of said flanges having a portion extending into an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said at least one flange being arranged to transmit torque to said at least two energy storing elements in response to rotation of said first flywheel, said flanges having portions which are disposed in the region of said fastening means and are closely adjacent each other.
 38. The apparatus of claim 1, wherein said at least one damper further comprises a plurality of flanges connected to said first flywheel by said fastening means and at least one of said flanges having a portion extending into an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said portion of said at least one flange being arranged to transmit torque to said at least two energy storing elements in response to rotation of said first flywheel, said flanges having portions which are spaced apart from each other in the direction of said axis and are disposed at least in part intermediate said fastening means and said at least two energy storing elements.
 39. The apparatus of claim 1, wherein said at least one damper further comprises a plurality of flanges driven by said first flywheel and at least one of said flanges comprises portions extending into an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said portions of said at least one flange being arranged to transmit torque to said at least two energy storing elements in response to rotation of said first flywheel, said at least two energy storing elements including coil springs having end convolutions and additional convolutions between the respective end convolutions, said end convolutions and said additional convolutions of each of said coil springs respectively having first and second pitches and said first pitches at least approximating said second pitches in substantially unstressed conditions of the respective coil springs, said portions of said at least one flange engaging said end convolutions and being configurated to transmit thereto torque in response to rotation of said first flywheel.
 40. The apparatus of claim 1, wherein said at least two energy storing elements comprise first coil springs and second coil springs at least partially within the respective first coil springs, said at least one damper further comprising at least one input member receiving torque from said first flywheel and including first and second portions extending into an at least substantially sealed chamber for portions at least of said at least two energy scoring elements to respectively transmit torque to said first and second coil springs in response to rotation of said first flywheel.
 41. The apparatus of claim 1, wherein said at least two energy storing elements include first springs and second springs at least partially surrounded by the respective first springs, and further comprising an enclosure defining an at least substantially sealed chamber for portions at least for said at least two energy storing elements, said enclosure including at least one wall connected to said second flywheel and including first and second abutments extending into said chamber and respectively receiving torque from said first and second springs in response to rotation of said first flywheel.
 42. The apparatus of claim 41, wherein said first abutments include deformed portions of said at least one wall and said second abutments include deformed parts of said deformed portions.
 43. The apparatus of claim 1, wherein said at least one damper further comprises at least one input member including portions extending into an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said portions of said at least one input member being arranged to transmit torque to said at least two energy storing elements in response to rotation of said first flywheel, arid further comprising means for centering said at least one input member on said first flywheel.
 44. The apparatus of claim 1, wherein said at least one damper further comprises at least one input member arranged to transmit torque to said at least two energy storing elements in response to rotation of said first flywheel, and further comprising means for centering said at least one input member on the output element of the prime mover.
 45. The apparatus of claim 1, wherein said at least one damper further comprises at least one input member arranged to transmit torque to said at least two energy storing elements in response to rotation of said first flywheel, said bearing being surrounded by said at least one input member.
 46. The apparatus of claim 1, wherein said at least one damper further comprises a plurality of input members arranged to transmit torque to said at least two energy storing elements in response to rotation of said first flywheel, one of said input members including said fastening means and further comprising means for centering said first flywheel on the output element of the prime mover, means for supporting said bearing and means for centering said second flywheel.
 47. The apparatus of claim 1, wherein said at least one damper further comprises at least one input member arranged to transmit torque from said first flywheel to said energy storing elements in response to rotation of said first flywheel, and further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including at least one wall and means for sealing said chamber including at least one sealing element disposed radially inwardly of said at least two energy storing elements between said at least one wall and at least one of a) a member connected with said first flywheel and b) said input member.
 48. The apparatus of claim 47, wherein said at least one sealing element includes a diaphragm spring.
 49. The apparatus of claim 47, wherein said enclosure further comprises a second wall connected with said at least one wall and with one of said, one of said walls including means for maintaining said fastening means in a predetermined position relative to said first flywheel.
 50. The apparatus of claim 1, further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including at least one wall having at least one opening and said fastening means including at least one fastener arranged to pass through said at least one opening.
 51. The apparatus of claim 1, wherein said fastening means comprises rotary threaded fasteners and further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including at least one wall having openings positioned to permit the passage of a tool having means for rotating said fasteners.
 52. The apparatus of claim 51, wherein said at least one wall has collars surrounding said openings.
 53. The apparatus of claim 52, wherein said enclosure further comprises at least one sealing element for said chamber, said at least one sealing element being disposed in the region of said openings.
 54. The apparatus of claim 1, further comprising an enclosure defining a chamber for portions at least of said at least two energy storing elements and means for at least substantially sealing said chamber including at least one diaphragm spring forming part of a friction generating device operating between said flywheels.
 55. The apparatus of claim 1, wherein said energy storing elements are disposed in a common plane extending at right angles to said axis and said at least one friction surface is provided on said second flywheel at least close to said plane.
 56. The apparatus of claim 1, wherein said means for fastening includes fasteners having heads disposed in a plane extending at least substantially at right angles to said axis, said bearing being disposed at least close to said plane.
 57. The apparatus of claim 1, wherein said fastening means includes threaded fasteners having heads disposed at least close to a common plane extending substantially at right angles to said axis, said at least one friction surface being provided on said second flywheel at said plane and said at least two energy storing elements being disposed radially between said heads and said at least one friction surface.
 58. The apparatus of claim 1, wherein said at least one damper further comprises at least one input member arranged to transmit torque to said energy storing elements in response to rotation of said first flywheel, said means for fastening including a plurality of fasteners and said at least one input member having a portion disposed between said chamber and said fasteners.
 59. The apparatus of claim 1, wherein the input element of the transmission has a profile disposed at a first radial distance from said axis upon connection of said friction clutch to said input element and said bearing is disposed at a second radial distance from said axis, said means for fastening including fasteners disposed at a third radial distance from said axis and further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including a radially inner portion disposed at a fourth radial distance from said axis, said at least two energy storing elements being disposed at a fifth radial distance from said axis and said enclosure further including a radially outer portion disposed at a sixth radial distance from said axis, said at least one friction surface being provided at said second flywheel at a seventh radial distance from said axis and at least four of said first to seventh distances being different from each other.
 60. The apparatus of claim 59, wherein said profile has a first diameter and said bearing has a different second diameter, said fasteners having heads forming a circle with a third diameter different from said first and second diameters, said radially inner portion of said enclosure having a fourth diameter different from said first to third diameters, said at least two energy storing elements forming an annulus having a fifth diameter different from said first to fourth diameters, said radially outer portion of said enclosure having a sixth diameter different from said first to fifth diameters and said at least one friction surface having a seventh diameter different from said first to sixth diameters.
 61. The apparatus of claim 59, wherein at least four of said profile, said bearing, said fasteners, said radially inner portion of said enclosure, said at least two energy storing elements, said radially outer portion of said enclosure, and said at least one friction surface are disposed at least close to a plane which is normal to said axis when said clutch is connected to the input element of the transmission.
 62. The apparatus of claim 1, wherein said means for fastening includes fasteners disposed at a first radial distance from said axis, said bearing being disposed at a lesser second distance from said axis.
 63. The apparatus of claim 1, wherein said means for fastening is disposed at a first radial distance from said axis, said bearing being disposed at a lesser second radial distance from said axis and said at least two energy storing elements being disposed at a third radial distance from said axis greater than said first distance.
 64. The apparatus of claim 1, wherein said means for fastening includes fasteners having portions disposed in a first plane extending at right angles to said axis and said at least two energy storing elements are disposed in a second plane at least close to or coinciding with said first plane.
 65. The apparatus of claim 1, further comprising an enclosure which defines an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including a portion disposed at a first radial distance from said axis, said at least two energy storing elements being disposed at a different second radial distance from said axis and said means for fastening being disposed at a third radial distance from said axis.
 66. The apparatus of claim 65, wherein said first distance exceeds said third distance and is less than said second distance.
 67. The apparatus of claim 1, wherein said bearing is disposed at a first radial distance from said axis and said means for fastening said first includes fasteners disposed at a lesser second radial distance from said axis.
 68. The apparatus of claim 1, wherein said at least two energy storing elements comprise coil springs each having a diameter and a length between approximately four and ten times said diameter.
 69. The apparatus of claim 1, wherein said at least two energy storing elements extend along arcs the sum of which is between approximately 252° and 342°.
 70. The apparatus of claim 1, wherein at least one of said at least two energy storing elements extends along an arc of at least 140°.
 71. The apparatus of claim 1, wherein said at least two energy storing elements include arcuate springs having a predetermined curvature which remains unchanged prior to insertion of said springs into and/or upon removal of said springs from an at least substantially sealed chamber for portions at least of said at least two energy storing elements.
 72. The apparatus of claim 1, wherein said at least two energy storing elements include at least one first energy storing element which opposes rotation of said flywheels relative to each other with a first force and at least one second energy storing element which opposes rotation of said flywheels relative to each other with a second force different from said first force.
 73. The apparatus of claim 1, wherein said at least two energy storing elements include at least one first energy storing element which opposes a first stage of rotation of said flywheels relative to each other and at least one second energy storing element which opposes a second stage of rotation of said flywheels relative to each other.
 74. The apparatus of claim 1, wherein said at least two energy storing elements include at least one coil spring having two end convolutions with a first pitch and at least one additional convolution disposed between said end convolutions and having a second pitch at least approximating said first pitch.
 75. The apparatus of claim 1, further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including a portion radially outwardly adjacent said at least two energy storing elements, and a body of wear resistant material interposed between said at least two energy storing elements and said portion and being engaged by said at least two energy storing elements under the action of centrifugal force in response to rotation of said first flywheel and said enclosure.
 76. The apparatus of claim 1, further comprising means for centering a housing of said friction clutch on said second flywheel.
 77. The apparatus of claim 1, wherein said friction clutch comprises a housing including a portion extending in the direction of said axis and at least partially surrounding said second flywheel.
 78. The apparatus of claim 77, wherein said axially extending portion of said housing centers the housing on said second flywheel.
 79. The apparatus of claim 77, wherein said axially extending portion of said housing is bonded to said second flywheel.
 80. The apparatus of claim 1, wherein said friction clutch comprises a housing and further comprising means for separably coupling said housing to said second flywheel.
 81. The apparatus of claim 1, wherein said friction clutch comprises a housing having means for separably coupling the housing to said second flywheel.
 82. The apparatus of claim 1, wherein said friction clutch comprises a clutch disc including a portion extending substantially radially of said axis, and further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including at least one wall having a side adjacent said portion of said clutch disc, said portion of said clutch disc having a side confronting and at least substantially conforming to said side of said at least one wall.
 83. The apparatus of claim 1, further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure having at least one wall provided with openings affording access to said fastening means, said friction clutch comprising a clutch disc adjacent said at least one wall and at least one of said clutch disc and said at least one wall having means for deflecting a viscous fluid at least partially filling said chamber when such fluid tends to escape from said chamber in the region of said clutch disc and said at least one wall.
 84. The apparatus of claim 1, wherein said friction clutch comprises a clutch disc having at least one opening affording access to said fastening means and permitting said fastening means to pass therethrough.
 85. The apparatus of claim 1, wherein said friction clutch has at least one opening affording access for a tool into engagement with said fastening means.
 86. The apparatus of claim 1, wherein said friction clutch comprises a housing rotatable with said second flywheel, a pressure plate rotatable with and disposed between said housing and said second flywheel with freedom of movement in the direction of said axis, a clutch disc disposed between said pressure plate and aid second flywheel and connectable to the input element of the transmission, and a clutch spring between said housing and said pressure plate, said clutch spring having a main portion bearing upon said pressure plate in an engaged condition of the clutch and prongs extending from said main portion, said clutch disc having a first outline and said main portion of said clutch spring being movable relative to said housing between a first position nearer to, and a second position more distant from, said clutch disc and having a second outline at least approximating said first outline in said first position of said main portion.
 87. The apparatus of claim 86, wherein said means for fastening includes a plurality of fasteners, said clutch disc having openings disposed in the region of said prongs and dimensioned to permit said fasteners to pass therethrough.
 88. The apparatus of claim 86, wherein said means for fastening comprises fasteners arranged to attach said first flywheel to the output element of the prime mover, said clutch spring having openings permitting the introduction of a tool into engagement with said fasteners.
 89. The apparatus of claim 1, wherein said friction clutch comprises: a housing rotatable with said second flywheel, a pressure plate disposed between and rotatable with said housing and said second flywheel, and having projections confronting said housing, and a clutch spring having openings for said projections.
 90. The apparatus of claim 89, wherein said clutch spring includes a set of prongs and slots between said prongs, said slots including narrower slots and wider slots constituting said openings.
 91. The apparatus of claim 1, wherein said friction clutch comprises a housing rotatable with said second flywheel, a pressure plate between said second flywheel and said housing, and leaf springs connecting said pressure plate to said housing with freedom of movement in the direction of said axis, said housing having a first side facing said second flywheel and a second side facing away from said second flywheel, at least a portion of each of said leaf springs being adjacent the second side of said housing.
 92. The apparatus of claim 1, wherein said friction clutch comprises a housing rotatable with said second flywheel, a pressure plate disposed between and rotatable with said housing and said second flywheel, a clutch spring between said housing and said pressure plate, and a seat assembly provided on said housing and tiltably mounting said clutch spring, said seat assembly having a first outline and said pressure plate having a first side facing said at least one friction surface and a second side facing said housing, said second side including a portion having a second outline at least substantially complementary to and adjacent said first outline.
 93. The apparatus of claim 92, wherein said clutch spring is tiltable at said seat assembly to engage and disengage the friction clutch, at least a portion of said seat assembly being overlapped by said pressure plate in the direction of said axis as well as radially of said axis in the disengaged condition of the friction clutch.
 94. The apparatus of claim 1, wherein said friction clutch comprises a housing, a clutch spring movable relative to said housing, at least one seat for said clutch spring, and means for securing said at least one seat to said housing, said means for securing being of one piece with said housing.
 95. The apparatus of claim 94, wherein said friction clutch further comprises a pressure plate disposed between said clutch spring and said second flywheel and having a side facing said housing, said at least one seat having a first outline and at least a portion of said side of said pressure plate having a second outline at least substantially conforming to said first outline.
 96. The apparatus of claim 1, further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including a wall adjacent said first flywheel and having a first outline, said first flywheel including a portion adjacent said wall and having a second outline at least substantially conforming to said first outline.
 97. The apparatus of claim 1, wherein at least a major portion of said first flywheel consists of metallic sheet material.
 98. The apparatus of claim 1, further comprising a starter gear on said first flywheel.
 99. The apparatus of claim 1, further comprising a starter gear on one of said flywheels, said starter gear comprising two overlapping layers of folded metallic sheet material.
 100. The apparatus of claim 1, further comprising a starter gear of one piece with one of said flywheels.
 101. The apparatus of claim 1, wherein said first flywheel comprises a main section and a mass carried by said main section.
 102. The apparatus of claim 101, wherein said mass is a casting.
 103. The apparatus of claim 101, wherein said mass comprises layers of folded metallic sheet material.
 104. The apparatus of claim 101, wherein said friction clutch comprises a housing including a portion extending in the direction of said axis and said mass includes a portion at least partially surrounding said portion of said housing.
 105. The apparatus of claim 1, wherein said at least one damper comprises a friction generating device.
 106. The apparatus of claim 105, wherein said friction generating device is disposed radially outwardly of said at least two energy storing elements.
 107. The apparatus of claim 105, wherein said at least one friction surface includes a first portion disposed at a first radial distance from said axis, an intermediate portion disposed at a greater second radial distance from said axis, and a third portion disposed at a greatest radial distance from said axis, said friction generating device being disposed at a fourth radial distance from said axis and said fourth distance at least matching said second distance.
 108. The apparatus of claim 105, wherein said friction generating device comprises at least one shoe having two friction surfaces disposed at different radial distances from said axis.
 109. The apparatus of claim 105, wherein said friction generating device includes at least one shoe in frictional engagement with said first flywheel.
 110. The apparatus of claim 109, wherein said second flywheel includes a portion engaging said shoe.
 111. The apparatus of claim 110, wherein said shoe and said portion of said second flywheel have a limited freedom of angular movement relative to each other about said axis.
 112. The apparatus of claim 105, wherein said friction generating device comprises a plurality of shoes and said second flywheel comprises portions engaging said shoes, at least some of said shoes and the respective portions of said second flywheel being movable relative to each other about said axis with different freedoms of angular movement.
 113. The apparatus of claim 105, wherein said friction clutch comprises a housing having a portion extending in the direction of said axis and forming part of said friction generating device.
 114. The apparatus of claim 105, wherein said first flywheel includes a mass forming part of said friction generating device.
 115. The apparatus of claim 105, wherein said friction clutch comprises a housing having a portion extending in the direction of said axis and being at least partially surrounded by a mass of said first flywheel, said friction generating device including at least one shoe at least close to a region where said mass surrounds said portion of said housing.
 116. The apparatus of claim 105, wherein said friction generating device comprises at least one energy storing element.
 117. The apparatus of claim 116, wherein said at least one energy storing element of said friction generating device is stressed in a direction substantially radially of said axis.
 118. The apparatus of claim 105, wherein said friction generating device includes at least one shoe carried by said first flywheel.
 119. The apparatus of claim 118, wherein said at least one shoe is clamped to said first flywheel.
 120. The apparatus of claim 105, wherein said friction generating device comprises a plurality of shoes spaced apart from each other in a circumferential direction of said flywheels.
 121. The apparatus of claim 105, wherein said friction generating device comprises at least one braking shoe having a friction generating portion of a plastic material.
 122. The apparatus of claim 1, wherein said friction clutch comprises a clutch disc and a clutch spring, at least one of said clutch disc and said clutch spring having at least one passage for a coolant.
 123. The apparatus of claim 1, wherein said friction clutch comprises a housing including a portion extending in the direction of said axis and having at least one passage for a coolant.
 124. The apparatus of claim 1, wherein said friction clutch comprises a housing including a wall extending substantially radially of said axis and having at least one passage for a coolant.
 125. The apparatus of claim 1, wherein said first flywheel has at least one passage for a coolant.
 126. The apparatus of claim 1, wherein said second flywheel has at least one passage for a coolant, said at least one passage being disposed radially outwardly of said chamber.
 127. The apparatus of claim 1, wherein said friction clutch comprises a clutch disc and further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure including at least one wall and said second flywheel having at least one first passage disposed radially outwardly of said chamber, said clutch disc having at least one second passage cooperating with said at least one first passage to define at least one path for the flow of a coolant through said clutch disc, along said at least one wall, through said second flywheel and toward said first flywheel.
 128. The apparatus of claim 1, further comprising an enclosure defining an at least substantially sealed chamber for portions at least of said at least two energy storing elements, said enclosure having at least one wall and said first flywheel having at least one passage establishing a path for the flow of a coolant along said wall and along said second flywheel.
 129. The apparatus of claim 1, wherein said first flywheel has at least one passage establishing a path for the flow of a coolant against said second flywheel.
 130. The apparatus of claim 1, wherein at least one of said flywheels has a first side at least two at said friction surface and an enlarged heat dissipating second side opposite said first side.
 131. The apparatus of claim 1, wherein said friction clutch comprises a pressure plate having a first side at said friction surface and an enlarged heat dissipating second side opposite said first side.
 132. The apparatus of claim 1, wherein at least one of (a) said friction clutch, (b) an enclosure for an at least substantially sealed chamber for portions at least of said at least two energy storing elements, and (c) at least one of said flywheels has at least one at least substantially vane-shaped air circulating portion.
 133. The apparatus of claim 1, wherein said flywheels and said friction clutch constitute a preassembled module, said means for fastening including means for securing said module to the output element of the prime mover.
 134. The apparatus of claim 133, wherein said means for securing includes fasteners forming part of said module.
 135. The apparatus of claim 134, wherein said module comprises means for non-separably confining said fasteners therein.
 136. The apparatus of claim 1, wherein said friction clutch is a push-type clutch.
 137. The apparatus of claim 1, wherein said friction clutch is a pull-type clutch.
 138. The apparatus of claim 1, further comprising means for limiting the magnitude of torque which said at least one damper transmits between said flywheels, said limiting means being at least substantially coplanar with said at least two energy storing elements and said second flywheel.
 139. The apparatus of claim 138, wherein said at least two energy storing elements are at least partially confined in a substantially annular at least partially sealed chamber.
 140. The apparatus of claim 138, wherein said bearing is at least substantially coplanar with said second flywheel, with said at least two energy storing elements and with said limiting means.
 141. The apparatus of claim 138, wherein said limiting means is disposed radially outwardly of said at least two energy storing elements and radially inwardly of said second flywheel.
 142. The apparatus of claim 1, wherein said at least two energy storing elements of said at least one damper extend in a circumferential direction of said flywheels.
 143. Apparatus for transmitting torque comprising: a first flywheel connectable with a rotary output element of a prime mover; a second flywheel rotatable with as well as relative to said first flywheel about a common axis and provided with at least one friction surface disposed at a first radial distance from said axis, said second flywheel being connectable with a rotary input element of a transmission by a friction clutch; a bearing interposed between said flywheels; and means for opposing rotation of said flywheels relative to each other including at least one damper having at least two energy storing elements disposed at a lesser second radial distance from said axis, said at least two energy storing elements being at least partially confined in said second flywheel and said second flywheel including a portion disposed radially outwardly of said at least two energy storing elements and extending in the direction of said axis and said means for opposing rotation further comprising a slip clutch operating between said flywheels in series with said at least two energy storing elements.
 144. The apparatus of claim 143, wherein said at least two energy storing elements of said at least one damper extend in a circumferential direction of said flywheels.
 145. Apparatus for transmitting torque comprising: a first flywheel; means for connecting said first flywheel with a rotary output element of a prime mover; a second flywheel rotatable with as well as relative to said first flywheel about a common axis and provided with at least one friction surface disposed at a first radial distance from said axis, said second flywheel being connectable with a rotary input element of a transmission by a friction clutch; a bearing interposed between said flywheels radially inwardly of said connecting means; and means for opposing rotation of said flywheels relative to each other including at least one damper having at least two energy storing elements disposed at a lesser second radial distance from said axis, said at least two energy storing elements being at least partially confined in said second flywheel and said second flywheel including a portion disposed radially outwardly of said at least two energy storing elements and extending in the direction of said axis.
 146. The apparatus of claim 145, wherein said at least two energy storing elements are disposed at least in part in an at least substantially sealed chamber.
 147. The apparatus of claim 145, wherein said at least two energy storing elements of said at least one damper extend in a circumferential direction of said flywheels.
 148. A flywheel arrangement, particularly for use in motor vehicles, comprising a first rotary flywheel connectable with a rotary output element of a prime mover; a second flywheel rotatable with as well as relative to said first flywheel about a common axis; a torsional vibration damper connecting said flywheels to each other; and a torque limiting device cooperating with one of said flywheels and including a portion extending radially outwardly of said axis beyond at least one component part of said damper and having friction surfaces engageable (a) with a first part of a friction clutch which first part is arranged to contact at least one friction lining of the clutch and (b) with at least one second part of the clutch, said second part being supported b said first art at least in the direction of said axis, said parts and said at least one friction lining and a pressure plate of said clutch being located at least substantially radially outwardly of said at least one component of said damper and at least one of said first part and said at least one second part of said clutch having at least one recess solely for the reception of said portion and said friction surfaces of said torque limiting device.
 149. The flywheel arrangement of claim 148, wherein said damper comprises a disc and walls flanking said disc and cooperating therewith to stress energy storing means forming part of said damper, said portion of said device forming part of at least one of said walls and including two arcuate elements disposed radially outwardly of said disc and extending toward each other and including substantially parallel sections contacting each other and together constituting said portion of said torque limiting device, said sections extending into said at least one recess.
 150. The flywheel arrangement of claim 148, wherein said at least one recess is defined by at least two of said parts.
 151. The flywheel arrangement of claim 148, wherein said portion of said torque limiting device has a plurality of sides and at least one of said sides contacts a friction lining disposed between said at least one side and at least one of said first and second parts and said pressure plate of said friction clutch. 